Department of Veterans Affairs Medical Center, Birmingham 35233; and University of Alabama at Birmingham, Birmingham, Alabama 35294
![]() |
ABSTRACT |
---|
Exacerbation of hypoxic
injury after restoration of oxygenation (reoxygenation) is an important
mechanism of cellular injury in transplantation and in myocardial,
hepatic, intestinal, cerebral, renal, and other ischemic
syndromes. Cellular hypoxia and reoxygenation are two essential
elements of ischemia-reperfusion injury. Activated neutrophils
contribute to vascular reperfusion injury, yet posthypoxic cellular
injury occurs in the absence of inflammatory cells through mechanisms
involving reactive oxygen (ROS) or nitrogen species (RNS). Xanthine
oxidase (XO) produces ROS in some reoxygenated cells, but other
intracellular sources of ROS are abundant, and XO is not required for
reoxygenation injury. Hypoxic or reoxygenated mitochondria may produce
excess superoxide (O
anoxia; ischemia; reperfusion
![]() |
BACKGROUND |
---|
Scope and Goals of the Review
This review focuses on reactive oxygen (ROS) and nitrogen species (RNS)-mediated mechanisms that lead to cellular injury during hypoxia and reoxygenation. Pathophysiology due to hypoxia per se is addressed when relevant to reoxygenation in the cellular context. Emphasis is on intracellular mechanisms that generate ROS and RNS and their roles in cellular signaling or as mediators of cell death.Clinical Importance of Ischemia-Reperfusion Injury
Both hypoxia (lack of oxygen relative to metabolic needs) and reoxygenation (reintroduction of oxygen to hypoxic tissue) are important in human pathophysiology because they occur in a wide variety of important clinical conditions. Prominent examples of tissue hypoxia that predispose to injury during reoxygenation include circulatory shock, myocardial ischemia, stroke, and transplantation of organs (67, 76, 102). Because diseases due to ischemia (e.g., myocardial infarction and stroke) are exceedingly common causes of morbidity and mortality and because organ transplantation is increasingly frequent, understanding the role of ROS and RNS in reoxygenation injury has the potential to lead to therapies that could improve public health. Cellular models of hypoxia-reoxygenation have provided useful tools for the study of reactive species-mediated mechanisms of cellular dysfunction in ischemia-reperfusion injury (127).Cellular Hypoxia and Reoxygenation Injury
Cellular necrosis inevitably follows extended periods of anoxia (i.e., oxygen absent) or severe hypoxia (i.e., oxygen supply decreased relative to metabolic demand). Hypoxic tolerance of various cell types differs, depending on the metabolic rate and intrinsic adaptive mechanisms of the tissue. Sublethal hypoxia, which may be transient and have no apparent consequences, can be followed by enhanced resistance to reoxygenation injury (conditioning), recovery, or exacerbated cellular injury (reoxygenation injury). Posthypoxic injury is due to a combination of changes in cellular energy charge, oxidant generating systems, and antioxidant defenses (76).Cellular hypoxia appears to be a key signal that activates
transcriptional regulators, including hypoxia-inducible factor-1 (HIF-1) (109), nuclear factor-B (NF-
B), activator
protein 1 (AP-1), and some mitogen-activated protein kinase (MAPK)
pathways (46). A redox-sensitive human antioxidant
response element induces gene expression in response to low oxygen
concentrations in some malignant cells (124). Two
overlapping manifestations of cell death, necrosis and
apoptosis, can be initiated by cellular hypoxia-reoxygenation (105).
Cells undergo specific changes in enzyme activities, mitochondrial
function, cytoskeletal structure, membrane transport, and antioxidant
defenses in response to hypoxia, which then collectively predispose to
reoxygenation injury (1). In contrast to the adaptive
effects of sublethal hyperoxia on ion transport (74), hypoxia downregulates proteins that maintain alveolar ion transport, including the Na+-K+-ATPase (sodium pump) and
the epithelial Na+ channel (ENaC) (23).
Hypoxia causes time- and concentration-dependent decreases in -,
-, and
-subunits of ENaC mRNA and decreases both
1- and
1-subunits of the
Na+-K+-ATPase. Hypoxia itself also impairs
cation transport in both A549 lung epithelial cells and rat alveolar
cells (73). Oxidative inhibition of membrane
Na+-K+- ATPase activity by
H2O2 produced as a result of
hypoxia-reoxygenation may be an important mechanism leading to
swelling and cytolysis (52). In lung hypoxia-reoxygenation
injury (e.g., after lung transplantation), reduced transepithelial
Na+ transport and fluid resorption by the alveolar
epithelium would increase pulmonary edema formation and impair its clearance.
A number of mitochondrial enzymes, including cytochrome oxidase and manganese superoxide dismutase (Mn SOD), decrease in activity in hypoxia (81, 101, 113), with predicted effects on oxygen metabolism. Cellular hypoxia inhibits expression of the multisubunit cytochrome oxidase (complex IV), the final intramitochondrial site of oxidative phosphorylation. Cytochrome oxidase activity of aerobic mouse lung macrophages decreases ~40% when incubated anaerobically for 96 h (113). Loss of cytochrome oxidase activity leads to cellular injury during reoxygenation, because absence of the final electron acceptor increases ROS production by more proximal complexes (33).
Cytoskeletal changes occurring in hypoxia would likely alter endothelial and epithelial permeability. ATP-depleted endothelial cells display shortening and disassembly of F-actin filaments (41), which lead to increased endothelial permeability (71). Hypoxia-reoxygenation has specific effects on the cytoskeleton of renal epithelial cells (88), which influence translational motion of membrane lipids. Cellular hypoxia may cause membrane protein aggregation, alterations in protein polarization (altered apical-basolateral orientation), protein degradation, and changes in molecular chaperones or growth factors. Renal epithelial cells develop increased membrane permeability, because of changes in transmembrane adhesion molecules, in a coordinated response characterizing the ischemic phenotype (12).
McCord (76) proposed the seminal model to explain how
reoxygenation worsens ischemic (i.e., hypoxic) injury through
increased ROS production. Superoxide radical (O) (7)] has been
implicated in posthypoxic cellular injury. ROS generated by hypoxia or
reoxygenation are now recognized as interacting with physiological
signal transducers (19, 46, 104, 110) rather than behaving
as simple reactants that peroxidize membrane lipids, oxidize DNA, or
denature enzyme proteins.
Free radicals (defined chemically as molecules containing an odd number
of electrons) (33), such as O) are detected during, and likely account for, some
manifestations of postischemic injury (Table
1). Perhaps of more physiological importance, both ROS and RNS can affect signal transduction in posthypoxic cells, and ROS are able to initiate cell death programs in
the form of apoptosis or necrosis. Diverse sources of ROS
(e.g., enzymes, mitochondria) exist normally within cells, some of
which produce excess reactive species during hypoxia-reoxygenation. Excess ROS from endogenous sources can account for autocrine and paracrine cellular injury during reoxygenation.
|
![]() |
ROS MEDIATE REOXYGENATION INJURY |
---|
General evidence for involvement of ROS in hypoxia-reoxygenation injury includes detection of lipid peroxidation and protein nitration products in reperfused brains (117), protection of various reperfused organs by antioxidant enzymes including SOD (76), and inhibition of postischemic injury by allopurinol, an XO inhibitor structurally related to purines (91). ROS (including ·OH radical) have been confirmed by electron paramagnetic resonance and spin trapping to occur in reoxygenated endothelial cells (135).
Neutrophils are important sources of ROS, but activated neutrophils are
not required for reoxygenation injury. Injury to cultured endothelial
cells, cardiac myocytes, hepatocytes, and other cell types occurs after
anoxia-reoxygenation in vitro, even in the absence of neutrophils.
Endothelial cells themselves subjected to anoxia-reoxygenation release
superoxide anions (O
In vitro reoxygenation decreased the viability of rat hepatocytes as a
function of time in hypoxia (26). Extracellular SOD and
catalase completely prevented reoxygenation injury, confirming involvement of at least extracellular ROS. Electron transport chain
inhibitors cyanide and antimycin A increased the severity of cellular
injury in this model, suggesting that mitochondria may be a source of
ROS (27). Reoxygenated hepatocytes released increased
quantities of O
Renal proximal tubular cells produce increased ROS [7-fold increase by 2',7'-dichlorofluorescein (DCF) fluorescence] after hypoxia-reoxygenation. Excess ROS appear capable of injuring the cells (89), because increased lipid peroxidation after reoxygenation is prevented by addition of SOD, catalase, dimethylthiourea (a radical scavenger), or deferoxamine (an iron chelator).
Hypoxia-reoxygenation also stimulates vascular endothelial cells to
release extracellular O
Hypoxia Apparently Increases ROS Production
Oxidants are produced in excess during reoxygenation, but ROS production also may increase in the reduced state that characterizes cellular hypoxia. Pulmonary artery smooth muscle cells, cardiomyocytes, and several other cell types produce increased ROS in hypoxia that are usually detected as oxidation of the fluorescent probe DCF (54, 133). Hypoxic pulmonary artery smooth muscle cells significantly increased DCF fluorescence fivefold above that of normoxic cells (55), and simulated ischemia (hypoxia and low glucose) of embryonic ventricular myocytes increased DCF fluorescence threefold over that of normoxic cells (133). Simulated in vitro ischemia of cardiomyocytes also increased dihydroethidine (DHE) oxidation due to ROS, so these observations are not simply an artifact related to the use of oxidizable DCF. Both myxothiazole and rotenone inhibited the DHE oxidation, suggesting that mitochondrial complexes III and I produced increased ROS. SOD inhibited the DHE oxidation, providing indirect evidence that the mitochondrial electron transport chain generated OHuman lung epithelial cells likewise have been observed to increase ROS
production significantly after 24-h incubation in hypoxia (<1%
O2) (69). Examples of typical data
from such experiments are shown in Fig.
1, which demonstrates increased DCF
fluorescence in hypoxia-preexposed lung epithelial cells by both
fluorescent microscopy and flow cytometry. The sulfhydryl compound
N-acetylcysteine and the antioxidants ebselen (a peroxide
scavenger) and Tempol (a superoxide scavenger) inhibited DCF
fluorescence. Ebselen was the most effective at inhibiting the DCF
signal from reoxygenated cells, suggesting that peroxides (probably
H2O2) accounted for the most of the increased
DCF fluorescence.
|
Hypoxia preexposure appears to increase cellular ROS production, probably from mitochondrial electron transport complexes. Excess ROS and RNS production has been well documented during reoxygenation. In vitro experiments have demonstrated that hypoxia-reoxygenation is sufficient to cause injury to various cell types, even in the absence of activated neutrophils. Both inhibitor (antioxidant) studies and detection of lipid and protein oxidation have confirmed a role for endogenously generated reactive species in cellular reoxygenation injury.
![]() |
INTRACELLULAR SOURCES OF ROS DURING HYPOXIA-REOXYGENATION |
---|
Xanthine Dehydrogenase-Oxidase
Two closely related enzymes potentially capable of ROS generation, aldehyde oxidase and XO, exist in most animals. Activities are concentrated mainly in the liver and intestine (63). XO is the more important source of both ORat tissues contain relatively high levels of XD-XO activity. Rat
pulmonary endothelial cells are protected equally from reperfusion injury by antioxidant enzymes or allopurinol, confirming that XO is an
important source of ROS during reoxygenation (1, 99). XO
also appears to be responsible for reoxygenation-induced
O
Ferrylhemoglobin
Hemoglobin and myoglobin, which are released into plasma after trauma, can mediate endothelial cell oxidative stress, and a ferrylhemoglobin intermediate has been detected in cellular hypoxia-reoxygenation models. Incubation of hemoglobin (Hb) or myoglobin during hypoxia-reoxygenation with endothelial cells causes transient oxidation of Hb to the reactive ferryl species (Fe4+). Lipid peroxidation, which results from exposure of endothelial cells to ferrylhemoglobin, increased after reoxygenation. Incubation of endothelial cells with Hb also caused a dose-dependent decrease in intracellular glutathione (GSH), confirming an oxidative stress (78). Nitric oxide (·NO) acts as an antioxidant to inhibit lipid peroxidation and injury due to ferrylhemoglobin, because 400 µM arginine inhibited both lipid peroxidation and formation of ferryl intermediate (3). Hemoproteins oxidized to their ferryl forms could account for heme-mediated injury of endothelial cells that have been stressed by hypoxia, reoxygenation, and glutathione depletion.NADPH Oxidase
Endothelial cells express a membrane NADPH oxidase, similar to the membrane enzyme complex that produces the respiratory burst in granulocytes. The membrane oxidase complex is an important source of ROS in ischemic mouse lungs (4) and probably other reoxygenated tissues. ROS produced by lungs exposed to normoxic ischemia or high-K+ buffer (24 mM) emanate from the membrane-associated NADPH oxidase complex in the vascular endothelial cells. p47phox, a subunit of the NAPDH oxidase, is detected by Western blotting of endothelial proteins. Endothelial cells adapted to flow in vitro for 2-7 days showed a nearly twofold increase in ROS production during simulated no-flow ischemia, compared with continuously perfused cells (129). Absence of flow causes flow-adapted cells to activate both NF-The GTPase binding protein Rac1 regulates the membrane NADPH oxidase
that produces ROS during mouse liver ischemia-reperfusion. A
dominant negative Rac1 construct completely inhibited
ischemia-reperfusion induced ROS production, NF-B
activation, and liver necrosis (86). The dominant negative
gene product (N17rac1) inhibits the intracellular ROS burst after
reoxygenation. N17rac1 expression protects smooth muscle cells,
fibroblasts, endothelial cells, and ventricular myocytes from
hypoxia-reoxygenation-induced death (58), indicating an
important role for Rac1. A constitutively active Rac1 mutant does not
increase intracellular ROS. Rac1 GTPase is, therefore, a necessary but
not sufficient component of the pathway leading to ROS production
during reoxygenation (87).
Multiple sources of ROS exist with cells and may account for increased reactive species production during reoxygenation. Although XD was identified early as a source of ROS during reoxygenation, other intracellular sources including redox cycling of iron and NAD(P)H oxidases have been demonstrated to produce ROS and contribute to oxidant stress during reoxygenation.
![]() |
ANTIOXIDANT DEFENSE MECHANISMS |
---|
Antioxidants Inhibit Cellular Reoxygenation Injury
Endogenous antioxidant systems are critically important in limiting reoxygenation-induced cellular damage. The preponderance of data shows that exogenous antioxidant enzymes and low-molecular-weight ROS scavengers inhibit reoxygenation injury in cellular models. However, studies employing scavengers do not by themselves identify specific ROS or RNS responsible for reoxygenation injury, and they do not exclude other mechanisms. The level and duration of hypoxia are themselves important in regulating levels of both the antioxidant enzymes and low-molecular-weight ROS scavengers. including glutathione, which ultimately might determine the extent of reoxygenation injury (60, 81, 112).Reoxygenation (after 12-min hypoxia) of hippocampal slices in vitro
increased LDH release and lipid peroxidation significantly. Exogenous
SOD and catalase inhibited injury, demonstrating involvement of ROS
(43), which appeared to arise from prostaglandin
synthesis, XO, and mitochondria, on the basis of the inhibitor profile.
O
Further indirect evidence from inhibitor studies for the involvement of ROS is that sodium salicylate, a nonspecific radical scavenger, prevents reoxygenation injury of rat livers perfused with hypoxic buffer (24). Livers released increased LDH and developed increased protein carbonyl and malondialdehyde content during reoxygenation. Salicylate (2 mM) inhibited development of markers of oxidant stress in reperfused livers, including LDH release, carbonyl formation, and malondialdehyde production.
Endogenous low-molecular-weight antioxidants are important in protection from reoxygenation injury. Thioredoxin (TRX; human T cell leukemia-derived factor) proteins act as disulfide oxidoreductases and electron donors for thioredoxin peroxidases. Thioredoxins function as disulfide bond reductants, similar in mechanism to N-acetylcysteine. Oxidized thioredoxin is reduced by thioredoxin reductases requiring NADPH.
Thioredoxin protects lung cells from reoxygenation injury. Viability of murine endothelial cells cultured in thiol-free medium decreased significantly after hypoxia-reoxygenation, but injury was diminished by exogenous TRX (100 µM). Because TRX does not decrease cellular ROS production or inhibit loss of GSH, it rather appears to act directly as a scavenger in reoxygenation models (47).
Effects of Hypoxia on Antioxidant Enzymes
Alveolar (AM) or peritoneal macrophages (PM) exist in high (PO2 > 100 mmHg) or low (PO2 < 20 mmHg) oxygen environments, respectively. Activities of the enzymes of oxidative phosphorylation and glycolysis differ significantly, with oxidative phosphorylation being higher in aerobic AM and glycolysis higher in hypoxic PM. Hypoxia decreases apparent expression of cytochrome oxidase in AM, a change in the electron transport system that would predispose to OMitochondrial DNA content, reflecting the abundance of mitochondria, does not change significantly in rat skeletal muscle cells cultured in hypoxia (81). However, a number of mitochondrial enzymes in these cells and in lung macrophages decrease in a coordinated fashion in hypoxia. Citrate synthase, NAD-isocitrate dehydrogenase, malate dehydrogenase, and cytochrome oxidase all decreased significantly after incubation of cells in hypoxia. (Mn SOD activity was not measured.) These data suggest a loss of mitochondrial enzyme activities due to hypoxia without a change in the number of mitochondrial. Brain capillary endothelial cells similarly respond to hypoxia preexposure by decreasing activities of GP, glutathione reductase (GR), catalase, and SOD, as well as cellular total GSH content (94). Such changes, which represent possibly adaptive downregulation of antioxidant defenses by unspecified mechanisms in hypoxia, would predispose to increased ROS production by reoxygenated mitochondria.
Global ischemia of isolated rabbit hearts decreases the rate of oxidative phosphorylation but does not eliminate H2O2 production. Hypoxia-reoxygenation significantly decreased activities of SOD and GP by ~40% in mitochondria isolated from rabbit hearts (112). Glucose-free hypoxia, used to model ischemia in vitro, also resulted in significantly depressed SOD and GP activities in perfused rat hearts. Rat hearts hypertrophied due to chronic pressure overload had increased SOD and GP activities (on a per mg protein basis), which appeared biologically important during recovery. Yet, during hypoxia, SOD activity decreased significantly in both control and hypertrophied hearts (60). Similarly, hypoxic exposure of cardiac myocytes (30 min) in vitro also caused a decrease in Mn SOD and GP activities but caused no change in catalase activity (59).
The response of alveolar type II (ATII) cells in primary culture to
hypoxia exemplifies the effects of hypoxia on antioxidant defenses. Exposure of isolated rabbit ATII cells to hypoxia in vitro
(<1% O2 for 24 h) caused a significant decrease in
Mn SOD activity and protein content (103). Mn SOD and
Cu,Zn SOD mRNA expression also decreased significantly in ATII cells
cultured in hypoxia for 24 h (48). The decrease in
ATII cell Mn SOD mRNA expression (69% compared with air controls by
semiquantitative PCR) was greater than the decrease in Cu,Zn SOD mRNA
expression. The decrease in Mn SOD mRNA content was due, in part, to
decreased Mn SOD mRNA stability in the hypoxic ATII cells. Mn SOD
enzyme specific activity did not change.
Hypoxia-induced decreases in cellular antioxidant enzymes, especially
Mn SOD, have potentially important biological consequences because they
could lead indirectly to cellular reoxygenation injury by exacerbating
oxidant stress (69). LDH release from lung epithelial cells maintained in hypoxia (<1% O2) for 24 h before
treatment with antimycin A plus carbonyl cyanide
p-trifluoromethoxyphenylhydrazone (FCCP), an in
vitro oxidant stress that increases mitochondrial O
The general response to hypoxia, therefore, appears to be decreased activity or expression of antioxidant defenses. Hypoxia-induced downregulation of antioxidant enzymes leads to reoxygenation injury, but the mechanism by which antioxidant enzyme expression is regulated by hypoxia is not known with certainty.
![]() |
RNS MEDIATE HYPOXIA-REOXYGENATION INJURY |
---|
·NO Itself Can Cause Cellular Injury
Both ROS and RNS mediate some aspects of reoxygenation injury, but ·NO can produce either damaging or protective effects (49). In many cell types, inducible nitric oxide synthase (iNOS) is induced by hypoxia. iNOS induction during hypoxia is controlled by HIF-1 (51), a basic helix-loop-helix-PAS heterodimer regulated by oxygen tension (125). ·NO reacts rapidly with OHuman umbilical vein endothelial cells exposed to anoxia-reoxygenation
release decreased quantities of prostacyclin (PGI2) in
response to thrombin, calcium ionophore A-23187, or arachidonic acid
(40). Endothelial cells decrease prostacyclin production during short (15 min) hypoxia exposures (126). Decreased
cyclooxygenase activity is due, in part, to ROS, because SOD and
catalase inhibit the decrease in PGI2 production. In
addition, nitration of PGI2 synthase correlates with
decreased PGI2 formation after reoxygenation. ONOO apparently nitrates and inactivates
PGI2 synthase, leaving unmetabolized prostaglandin
H2 (PGH2), which can cause vasospasm, platelet
aggregation, and thrombus formation by stimulating the thromboxane
A2 (TXA2)/PGH2 receptor
(134).
· NO itself may be cytotoxic, especially when
present at supraphysiological concentrations (57). ·NO
can react reversibly with enzyme 4Fe-4S (iron-sulfur) centers, yielding
inactive 4Fe-4S-·NO derivatives. ·NO thus inactivates mitochondrial
aconitase, NAD-ubiquinone oxidoreductase (complex I), and
succinate-ubiquinone reductase (complex II), resulting in inhibited
mitochondrial respiration (32). ·NO inhibits respiration
directly by binding cytochrome oxidase. ·NO-derived reactants,
especially ONOO, also potentiate inflammation by
inactivating Mn SOD protein through nitration of its tyrosine residues
(72), as well as by depleting low-molecular-weight
antioxidants like GSH and ascorbate.
·NO Protects Cells From Hypoxia-Reoxygenation Injury
In contrast to its cytotoxic effects, ·NO more often acts as an antioxidant and attenuates reoxygenation injury. ·NO is capable of inhibiting lipid peroxidation chain reactions, and ·NO has clear protective effects in many cellular hypoxia-reoxygenation models. Hypoxia preexposure increases iNOS mRNA in myocardial cells and protects against subsequent damage from prolonged hypoxia (98). ·NO from hippocampal constitutive NOS (cNOS) may be involved in neuroprotection afforded by hypoxic preconditioning, because NOS inhibition blocks the development of preconditioning after anoxia exposures (17).Activation of cGMP-dependent pathways by ·NO appears to be protective. For example, L-arginine, an NOS substrate, limits myocardial cell death due to hypoxia-reoxygenation through a cGMP-dependent mechanism (2). L-Arginine increases cGMP in cardiac myocytes and inhibits LDH release due to reoxygenation (2). Cardiomyocytes preconditioned with 90 min of simulated ischemia (i.e., near anoxia and glucose-free medium) followed by 30-min reoxygenation were protected from subsequent ischemia (98). The NOS inhibitor NG-nitro-L-arginine methyl ester (L-NAME) blocked preconditioning, and the ·NO donor S-nitroso-N-acetyl-L-penicillamine (SNAP) protected cells from reoxygenation. Preconditioning required synthesis of ·NO and was cGMP-dependent, but protection due to ·NO appeared independent of protein kinase C (PKC) activation or ATP-sensitive K+ (KATP) channels. Similarly, decreased cNOS expression due to reoxygenation appears to be related to development of apoptosis of coronary artery endothelial cells. Anoxia-reoxygenation of the cells significantly decreased cNOS and Bcl-2, whereas it increased Fas expression (70).
The protective effects of ·NO depend critically on the
PO2 and balance of ·NO and
O
Consistent with apparent antioxidant effects of ·NO noted above, we
observed that inhibition of endogenous NOS activity markedly worsens
lung epithelial cell reoxygenation injury in vitro. Cultured, human
lung epithelial cells were incubated with aminoguanidine (50 µM), an
inhibitor of iNOS, during reoxygenation. iNOS inhibition markedly
increased LDH release, suggesting that ·NO inhibits reoxygenation injury [similar results have been found with
NG-monomethyl-L-arginine
(L-NMMA)]. An example of such data is shown in Fig.
2. Similarly, L-NMMA
significantly increased cytolysis of Mn SOD-deficient mouse lung
fibroblasts (/
) during reoxygenation (Jackson and Li, unpublished
data), again suggesting that ·NO, probably derived from iNOS,
modulates oxidative stress in reoxygenated lung cells.
|
Effects of ·NO on Mitochondrial Function During Hypoxia-Reoxygenation
·NO has important effects on cellular respiration and mitochondrial ROS production, which could either contribute to or protect from hypoxia-reoxygenation injury. Cellular respiration is regulated by ADP availability to F2-ATPase, O2 availability to cytochrome oxidase, and the concentration of ·NO (10). ·NO participates in redox reactions in the mitochondrial matrix, which regulate both intramitochondrial ·NO concentration itself and production of other reactive species (OIn contrast, ONOO irreversibly inhibits
mitochondrial complexes I, II, IV, and V, as well as aconitase.
Decreased maximal uptake rate and increased affinity constant for
O2 of the enzyme characterize ONOO
inhibition
of cytochrome oxidase (111).
Intramitochondrial ONOO
reacts with NADH, changing
the mitochondrial redox state. ONOO
treatment of
submitochondrial particles leads to ubisemiquinone autooxidation
increasing O
Mitochondrial proteins such as Mn SOD may be nitrated chemically by
high concentrations of ONOO (200 µM in vitro). However,
the intramitochondrial steady-state concentration of ONOO
remains around 2 nM (121), indicating that this mechanism
may be less relevant in vivo. Mitochondrial creatine kinase (CK) exists predominantly as an octamer, and ischemia decreases the ratio of octamers to dimeric forms and so inhibits CK activity. An identical decrease in CK activity and change in structure occurs after
ONOO
exposure that inhibits transport of high-energy
phosphate out of mitochondria, resulting in impaired cardiac
performance (114).
Although ·NO can injure cells directly or after reaction
with O, much
evidence indicates that ·NO is protective against cellular hypoxia-reoxygenation injury. Probable protective mechanisms include innate antioxidant properties of ·NO: increasing cellular cGMP, and
partial inhibition of cellular respiration.
![]() |
ROLE OF MITOCHONDRIA IN HYPOXIA-REOXYGENATION INJURY |
---|
Mitochondrial ROS Production
ROS and possibly RNS generated by mitochondria may damage the organelles themselves and other cellular constituents during reoxygenation. Protein carbonyls, a marker of oxidant stress, are detected in mitochondrial proteins after 10-min hypoxia and 5-min reoxygenation (100). The mitochondrial electron transport chain generates superoxide anions radicals (OEffects of Hypoxia on Mitochondrial ROS Production
The respiratory electron transport chain becomes reduced (i.e., the complexes harbor electrons) during anoxia, and the reduced state potentiates OEffects of Reoxygenation on Mitochondrial Function
Decreased Mn SOD activity, protein, or gene expression caused by hypoxia could influence the steady-state concentration of mitochondrial OMitochondrial complex I dysfunction occurs after reoxygenation of
hypoxic mitochondria (62). Complex I defects increase cellular production of ROS, which may influence Mn SOD expression (93). Reoxygenated kidney tubule cells develop energy
deficits due to complex I dysfunction that occur before onset of the
mitochondrial permeability transition (MPT) or loss of cytochrome
c. Supplementation with citric acid cycle metabolites that
anaerobically generate ATP may prevent energy deficits
(125). Anaerobic metabolism of -ketoglutarate and
aspartate generate sufficient ATP to maintain mitochondrial membrane
potential. Proximal tubules are protected from
hypoxia-reoxygenation-induced mitochondrial injury by anaerobic metabolism of citric acid cycle intermediates and of succinate (130). Whereas complex I dysfunction occurs as a result of
ROS produced during reoxygenation, substrates that bypass complex I
provide sufficient energy to maintain viability of reoxygenated cells
(131).
Transient, but large, cellular and mitochondrial Ca2+ fluxes occur during hypoxia-reoxygenation. Elevated intracellular Ca2+ concentration ([Ca2+]i) causes mitochondrial depolarization. Anoxia depolarizes guinea pig ventricular myocyte mitochondria, and recovery of normal mitochondrial membrane potential is essential to avoid hypercontracture. Reoxygenation caused significant elevation in intramitochondrial [Ca2+], the amplitude of which correlated with the extent of hypercontracture (28). Intramitochondrial [Ca2+] also increases markedly ([Ca2+]i > 350 nM) during rat cardiomyocyte hypoxia-reoxygenation, whereas cytosolic [Ca2+] falls. Myocyte mitochondrial Ca2+ uptake during hypoxia occurs largely through the Na+/Ca2+ exchanger, rather than the Ca2+ uniporter (38). Extracellular catalase inhibited the increase in myocyte [Ca2+] and [Na+] content and LDH release due to hypoxia-reoxygenation, indicating that extracellular H2O2 contributed to the ion fluxes.
Release of Ca2+ from storage sites stimulates Ca2+-dependent proteases, nucleases, and phospholipases that trigger apoptosis. Ca2+ leaves mitochondria during reoxygenation through pore formation, reversal of uniport influx carrier, the Ca2+/H+ antiport system, or channel-mediated Ca2+ pathways. Increased intracellular Ca2+ also appears to be related to oxidation of adenine nucleotides or by thiol oxidation, because overexpression of the antiapoptotic protein Blc-2, which has antioxidant properties, in mitochondrial membranes inhibits Ca2+ efflux due to oxidants (31).
The long-lived oxidant H2O2 stimulates human
aortic endothelial cell [Ca2+] oscillations.
Reoxygenation similarly initiates [Ca2+] oscillations,
which depend on Ca2+ release from the intracellular pool
and require extracellular Ca2+. The Ca2+
oscillations caused by NADPH oxidase-derived
H2O2 appear to play an important role in signal
transduction (44). Removal of Ca2+ from the
medium or Ca2+ chelation prevented killing of rat
hepatocytes by rotenone and anoxia, but not by cyanide.
Ca2+ depletion prevented the MPT in anoxic or
rotenone-treated cells, and Ca2+ influx is required to kill
cells after complex I inhibition (92). Although anoxia is
associated with mitochondrial Ca2+ influx, hypocalcemic
medium does not always prevent reoxygenation injury. Low extracellular
Ca2+ at the time of reoxygenation significantly worsened
cellular injury of rat hepatocytes (61). When the
Na+/H+ exchanger and
Na+-HCO
Preconditioning involves both the KATP channel and ROS production. KATP channel antagonists and antioxidants blocked both preconditioning and ROS production. Transfer and expression of genes encoding ATPase channel subunits render COS-7 monkey kidney cells resistant to hypoxia-reoxygenation injury (50).
Mitochondrial complex III is an important site of O
![]() |
REACTIVE SPECIES IN INTRACELLULAR SIGNALING |
---|
ROS act as signaling molecules in various cell types
(46, 119), participating in or modifying physiological
events related to receptor-ligand binding and transcriptional
activation (35, 39, 90). Intracellular signaling pathways
are implicated in cell death following reoxygenation, although the
specific pathway leading to apoptosis or necrosis might vary
among cell types. Several protein kinase signaling pathways involved in
cellular reoxygenation injury are shown in Fig.
3. ROS interact with a number of specific
molecular targets in reoxygenated cells, including extracellular
signal-regulated kinases (ERK) and MAPK that mediate proliferation,
stress-activated protein kinases (SAPK) implicated in
apoptosis, NF-B, and several caspases (132).
The GTPase binding protein Rac1 regulates some kinases [e.g., SAPK,
p38 MAPK, and c-Jun NH2-terminal kinases (JNK)]. These
kinases may be regulated further by ROS from NAD(P)H oxidase, which
requires Rac1 for activity (46). Inhibition of Rac1
lessens both ROS production and reoxygenation injury (58).
|
ROS also regulate or participate in growth, apoptosis, and the
adaptive response to injury or stress (35). Platelets
exposed to anoxia-reoxygenation generate O
Stress Kinases, JNK, and AP-1
ROS produced during reoxygenation appear to stimulate SAPK, including JNK and p38 MAPK (65). Anoxia followed by hyperoxia (reoxygenation) causes apoptosis of mouse embryo fibroblast (NIH/3T3) cells. Fibroblast arrest in G1 during anoxia was reversed on reoxygenation. c-jun and c-fos expression increased during anoxia. AP-1 binding increased markedly during reoxygenation, as did poly(ADP-ribose) polymerase (PARP) cleavage and caspase-3 activation. Induction of c-jun/c-fos (AP-1) expression during hypoxia was followed by PARP activation and histone H1 ADP-ribosylation. Activation of the AP-1 pathway was essential to initiation of programmed cell death (21).Hypoxia-reoxygenation of cardiac myocytes caused a 10-fold increase in
phosphorylation of the c-jun transcription factor. c-jun activation correlated with a decrease in GSH content,
indicating that AP-1 activation occurred in association with oxidant
stress. JNK activity was inhibited by a free radical spin trap
(-phenyl-N-tert-butylnitrone) and
N-acetylcysteine, a sulfhydryl compound. Phosphorylation and activation of c-Jun protein are linked directly to intracellular redox
status (65). SAPK activation also leads to
H2O2-induced apoptosis and upregulation
of intercellular adhesion molecule (ICAM)-1 (46).
Supporting evidence for activation of kinase pathways by ROS during reoxygenation includes inhibition of hypoxia-reoxygenation-induced apoptosis by an antisense oligonucleotide targeted to JNK-1. Human kidney cells in vitro undergo apoptosis during reoxygenation after 48-h hypoxia. Reoxygenation causes a time-dependent increase in activation of JNK-1, while p38 MAPK is activated by hypoxia. Activation of the JNK signaling cascade leads to apoptosis during hypoxia-reoxygenation (34).
Transient hypoxia causes apoptosis of developing rat brain neurons due to activation of AP-1-related transcription factors and JNK kinases. AP-1 expression increases in neurons during hypoxia. JNK-1 and JNK-3 are induced after 48-h reoxygenation. Hypoxia exposure increased c-Jun, Jun B, Jun D, c-Fos, and Fos-related protein expression. JNK-1 and JNK-3 both increased transiently 48 h after reoxygenation, when apoptosis occurred (22).
JNK-1 activity translocated to the nucleus increases during reperfusion, at which time JNK-1 is serine-phosphorylated. An upstream kinase, SAPK/ERK kinase 1 (SEK1), activates JNK-1 in the nucleus. Another upstream kinase for the MAPK, MAPK/ERK kinase 1 (MEK1), in contrast, remains localized to the cytosol. Increased JNK-1 activity after ischemia depends on its translocation to the nucleus and activation of upstream protein kinases (probably SEK1) during reoxygenation (80).
Protein Kinase C
PKC-Chemical hypoxia (produced by the reducing agent thioglycolic acid) and lack of glucose increased permeability of cultured human dermal endothelial cells. Intracellular [Ca2+] increased as well under those conditions. Permeability changes due to hypoxia and low glucose could be blocked by chelating Ca2+, PKC, and protein kinase G (PKG) inhibition or by inhibition of p38 MAPK-1. Ca2+-induced dissociation of cadherin-actin and occludin-actin junctions might mediate increases in endothelial permeability (88), through pathways that involve PKC, PKG, and MAPK.
Ischemic preconditioning of hepatocytes decreases Na+ accumulation during hypoxia and decreases cellular death, as does PKC activation (16). PKC appears to activate H+ extrusion and maintain intracellular pH.
Nuclear Factor-B
NF-B activation and nuclear translocation is required for
development of tolerance to anoxia-reoxygenation (18).
Inhibition of ·NO synthase during a second anoxia-reoxygenation
challenge prevents both inhibition of polymorphonuclear neutrophil
adherence and NF-
B activation. Thus, while NF-
B
activation is associated with the vascular inflammatory response in
vivo, NF-
B activation is required for the development of tolerance
to hypoxia-reoxygenation in vitro.
Reactive species may act as intracellular signals, or they may interact
with specific molecules of intracellular signaling cascades.
Stress-activated protein kinases, particularly JNK and p38 MAPK, have
been most strongly associated with hypoxia-reoxygenation injury.
PKC- appears to be responsible for induction of MAPK activity during
reoxygenation. NF-
B activation by hypoxia-reoxygenation can be
blocked by ·NO, and NF-
B appears to be required for development of
tolerance to hypoxia-reoxygenation.
![]() |
REACTIVE SPECIES MECHANISMS OF CELL DEATH DURING REOXYGENATION |
---|
Apoptosis
Both apoptosis and necrosis (and likely intermediate forms of cell death, as well) are linked to excess intracellular ROS production (70). ROS, for example, mediate PARP cleavage and lead to apoptosis (77). Apoptosis initiated by oxidant stress involves increased mitochondrial permeability and release of cytochrome c (14). Downstream signaling and enzymatic mechanisms, including activation of caspases, are all regulated by oxidant mechanisms (29). Apoptosis depends on the availability of cellular ATP, so reoxygenation could potentiate apoptosis by restoring cellular energy (77). Antioxidants inhibit DNA fragmentation and PARP cleavage, suggesting that ROS are responsible for these manifestations (79). Hypoxia-reoxygenation itself enhances expression of CD95L (APO-1/Fas), a transmembrane protein that induces apoptosis by ligand binding and subsequent activation of caspases (123).Bcl-2 may exert some of its antiapoptotic effects through apparent
antioxidant actions, because Bcl-2 inhibited
H2O2 production due to ceramide or tumor
necrosis factor-. Bcl-2 overexpression allows cells to adapt to ROS
overproduction (31). Apoptosis in an endothelial
reperfusion model also required activation of NF-
B, because NF-
B
decoy oligodeoxynucleotides decreased the number of TUNEL (TdT-mediated
dUTP nick end labeling)-positive cells. NF-
B augments
apoptosis by suppressing the antiapoptotic Bcl-2 expression
in hypoxia (75).
Bax and p53 are induced in some cell types that undergo apoptosis after hypoxia. Proapoptotic Bax and the interleukin-converting enzyme subfamily of caspases increased after exposure of neurons to hypoxia followed by reoxygenation (8). Induction of Bax and p53 expression preceded neuronal apoptotic death.
Apoptosis observed after in vitro reoxygenation of cardiomyocytes is associated with activation of caspases-3 and -9 and appearance of cytochrome c in the cytosol. Initiation of apoptosis depends on mitochondrial release of a caspase-activating factor (probably cytochrome c); Bcl-2 overexpression blocks both cytochrome c release and activation of caspases-3 and -9 from the reoxygenated cells (53). Hypoxia-reoxygenation decreases Bcl-2 expression and increases Fas protein, changes associated with cardiomyocyte apoptosis and necrosis. Caspase inhibition and Bcl-2 overexpression inhibit apoptosis during reoxygenation, but they do not inhibit death due to hypoxia.
Hypoxia causes accumulation of p53, as well as hypophosphorylated retinoblastoma protein (pRB), in S-phase melanoma cells. p53 protein was higher in S phase than in G1 or G2, while pRB was not cell-cycle dependent. However, hypoxic induction of p53 did not arrest cell growth (25). Hypoxia also induces p53 and enhances apoptosis of cultured trophoblasts. Apoptosis in hypoxic trophoblasts involves alterations in p53 and Bax expression, because both are increased in hypoxia, whereas Bcl-2 is decreased (68). In contrast to the proapoptotic effects of p53, epithelial growth factor and enhanced differentiation protect cells from hypoxia-induced apoptosis (68).
Hypoxia per se is insufficient to initiate apoptosis in some cells. Apoptosis of rapidly contracting hypoxic myocytes occurred only when extracellular pH decreased. Reoxygenation of the hypoxic acidotic myocytes induced apoptosis in 23-30% of cells, independently of changes in p53 expression. Therefore, exogenous lactic acid during reoxygenation can induce programmed cell death without an increase in cellular p53 (128).
Bax protein translocates to mitochondria during reoxygenation and triggers cell death. Maintenance of glucose during hypoxia prevented Bax translocation to mitochondria and reoxygenation injury, in addition to maintaining intracellular ATP levels. Likewise, Bcl-2 overexpression in kidney tubule cells minimized apoptosis. Bcl-2 overexpression preserved mitochondrial integrity and prevented both apoptosis (glucose present) and necrosis (glucose absent), suggesting a common pathway involving mitochondrial dysfunction in cell death (104).
Hypoxic preconditioning activates transcription of Bcl-2 and heat shock protein 70 (HSP70), which are apparently protective, in neurons. Preconditioning occurs, in part, by expression of antiapoptotic gene products including Bcl-2, HSP-70, and regulatory components of the cell cycle (9). Likewise, overexpression of HSP-70 attenuates hypoxic injury of coronary endothelial cells (115). HSP-72 appears to be an important part of the normal response to stress, protecting from hypoxia-reoxygenation. HSP-72 translocates to the cytoskeleton after of hypoxia-reoxygenation (106). Inhibition of HSP-72 using antisense oligonucleotides increases reoxygenation injury of cardiomyocytes (83).
Mitochondria are critical to initiation of apoptosis in
reoxygenated cells. Increased ROS production, cytochrome c
release from mitochondria, and cell death during reoxygenation are
linked. Mitochondria from apoptotic cells produce increased
quantities of O
Necrosis
Necrosis is associated with tissue inflammation, but cytolysis occurs in cell culture reoxygenation models as well. Inhibition of apoptosis, because of lack of energy due to hypoxia-induced ATP depletion, may predispose to necrosis, and mechanisms of cell death typically overlap. DNA "laddering" into 180-bp fragments may occur in necrosis, although nucleosomal laddering is more characteristic of apoptosis. Multiple assays, including morphological examination, are required to define the actual characteristics (apoptotic, necrotic, or overlap) of cell death due to reoxygenation.Human lung epithelial cells clearly undergo necrosis rather than
apoptosis because of excess superoxide production in
mitochondria after preexposure to hypoxia (1% O2 for
24 h). The Mn SOD activity of the cell decreases by ~50% after
24 h in hypoxia, as observed previously in ATII cells
(103). The mechanism of decreased Mn SOD expression
involves decreased stability of Mn SOD mRNA rather than direct
inhibition of the Mn SOD promoter (85). ATP content did
not change significantly, so cellular injury or lack of
apoptosis could not be attributed to lack of energy per se.
Antimycin A and FCCP generate excess mitochondrial O
Cellular injury after reoxygenation was associated with increased ROS production. N-acetylcysteine (1 mM), a sulfhydryl compound, partially inhibited increased DCF fluorescence after hypoxia and protected the lung epithelial cells from cytolysis during incubation with antimycin A and FCCP. Inhibition of both ROS production and cytolytic damage by N-acetylcysteine supports the notion that oxidants produced by the epithelial cells are involved in reoxygenation injury. Thus lung epithelial cells may undergo necrosis directly without preliminary apoptosis, as a result of increased susceptibility to oxidant stress after hypoxia preexposure.
Thus both apoptosis and necrosis occur after hypoxia-reoxygenation injury, and both appear dependent on increased reactive species production. Apoptosis after reoxygenation is associated with activation of caspases, and both caspase inhibition and Blc-2 overexpression inhibit apoptosis. Mitochondria are involved in posthypoxic apoptosis through increased ROS production and cytochrome c release. Cells are capable of undergoing necrosis directly after reoxygenation, and necrosis is also related to increased ROS production.
![]() |
SUMMARY AND CONCLUSIONS |
---|
Adequate oxygenation is critical to cellular viability. The "paradox" of reoxygenation injury can be understood in terms of counteradaptive changes occurring in hypoxia that predispose to cellular dysfunction, apoptosis, and necrosis during reoxygenation. These changes include enhanced reduction of the mitochondrial respiratory chain, conversion of XD to XO, downregulation of antioxidant systems, increased reactive species formation, and activation of signaling pathways. Specific molecular mechanisms and pathways involving ROS and RNS that lead to necrosis or apoptosis during reoxygenation have been identified. Knowledge of these pathways has led to clinical attempts at minimizing reoxygenation injury in transplantation and myocardial reperfusion.
![]() |
ACKNOWLEDGEMENTS |
---|
We thank M. Kennedy for transcribing the manuscript.
![]() |
FOOTNOTES |
---|
This research was supported by The Veterans Affairs Research Service, National Institutes of Health Grants HL-57801 and DK-97010, Office of Naval Research Grant N00014-97-1-03-09, and an American Heart Association-Alabama Affiliate Grant-in-Aid.
Address for reprint requests and other correspondence: R. Jackson, Division of Pulmonary, Allergy and Critical Care Medicine, Univ. of Alabama at Birmingham, Rm. 215 Tinsley Harrison Tower, 1900 Univ. Boulevard, Birmingham, AL 35294-0006 (E-mail: rjackson{at}uab.edu).
10.1152/ajpcell.00112.2001
![]() |
REFERENCES |
---|
1.
Acosta, D,
and
Li CP.
Injury to primary cultures of rat heart endothelial cells by hypoxia and glucose deprivation.
In Vitro
15:
929-934,
1979[ISI][Medline].
2.
Agullo, L,
Garcia-Dorado D,
Inserte J,
Paniagua A,
Pyrhonen P,
Llevadot J,
and
Soler-Soler J.
L-Arginine limits myocardial cell death secondary to hypoxia-reoxygenation by a cGMP-dependent mechanism.
Am J Physiol Heart Circ Physiol
276:
H1574-H1580,
1999
3.
Agnillo, FD,
Wood F,
Porras C,
Macdonald VW,
and
Alayash AI.
Effects of hypoxia and glutathione depletion on hemoglobin- and myoglobin-mediated oxidative stress toward endothelium.
Biomed Biochim Acta
1495:
150-159,
2000.
4.
Al-Mehdi, AB,
Zhao G,
Dodia C,
Tozawa K,
Costa K,
Muzykantov V,
Ross C,
Blecha F,
Dinauer M,
and
Fisher AB.
Endothelial NADPH oxidase as the source of oxidants in lungs exposed to ischemia or high K+.
Circ Res
83:
730-737,
1998
5.
Beauchamp, P,
Richard C,
Tamion F,
Lallemand F,
Lebreton JP,
Vaudry H,
Daveau M,
and
Thuillez C.
Protective effects of preconditioning in cultured rat endothelial cells: effects on neutrophil adhesion and expression of ICAM-1 after anoxia and reoxygenation.
Circulation
100:
541-546,
1999
6.
Becker, LB,
Vanden Hoek TL,
Shao ZH,
Ch. Li Q,
and
Schumacker PT.
Generation of superoxide in cardiomyocytes during ischemia before reperfusion.
Am J Physiol Heart Circ Physiol
277:
H2240-H2246,
1999
7.
Beckman, JS,
Beckman TW,
Chen J,
Marshall PA,
and
Freeman BA.
Apparent hydroxyl radical production by peroxynitrite: implications for endothelial injury from nitric oxide and superoxide.
Proc Natl Acad Sci USA
87:
1620-1624,
1990[Abstract].
8.
Bossenmeyer, C,
Chihab R,
Muller S,
Schroeder H,
and
Daval JL.
Hypoxia/reoxygenation induces apoptosis through biphasic induction of protein synthesis in cultured rat brain neurons.
Brain Res
787:
107-116,
1998[ISI][Medline].
9.
Bossenmeyer-Pourie, C,
Koziel V,
and
Daval JL.
Effects of hypothermia on hypoxia-induced apoptosis in cultured neurons from developing rat forebrain: comparison with preconditioning.
Pediatr Res
47:
385-391,
2000
10.
Boveris, A,
Costa LE,
Poderoso JJ,
Carreras MC,
and
Cadenas E.
Regulation of mitochondrial respiration by oxygen and nitric oxide.
Ann NY Acad Sci
899:
120-135,
2000.
11.
Brown, GC.
Nitric oxide and mitochondrial respiration.
Biochim Biophys Acta
1411:
351-369,
1999[ISI][Medline].
12.
Bush, T,
Keller SH,
and
Nigam SK.
Genesis and reversal of the ischemic phenotype in epithelial cells.
J Clin Invest
106:
621-626,
2000
13.
Cadenas, E,
and
Davies KJA
Mitochondrial free radical generation, oxidative stress and aging.
Free Radic Biol Med
29:
222-230,
2000[ISI][Medline].
14.
Cai, J,
and
Jones DP.
Superoxide in apoptosis.
J Biol Chem
273:
11401-11404,
1998
15.
Carceni, P,
Ryu HS,
Van Theil DH,
and
Borle AB.
Source of oxygen free radicals produced by rat hepatocytes during postanoxic reoxygenation.
Biomed Biochim Acta
1268:
249-254,
1995.
16.
Carini, R,
De Cesaris MG,
Spendore R,
Bagnati M,
and
Albano E.
Ischemic preconditioning reduces Na+ accumulation and cell killing in isolated rat hepatocytes exposed to hypoxia.
Hepatology
31:
166-172,
2000[ISI][Medline].
17.
Centeno, JM,
Orti M,
Salom JB,
Sick TJ,
and
Perez-Pinzon MA.
Nitric oxide is involved in anoxic preconditioning neuroprotection in rat hippocampal slices.
Brain Res
836:
62-69,
1999[ISI][Medline].
18.
Cepinskas, G,
Lush CW,
and
Kvietys PR.
Anoxia/reoxygenation-induced tolerance with respect to polymorphonuclear leukocyte adhesion to cultured endothelial cells: a nuclear factor-B-mediated phenomenon.
Circ Res
84:
103-112,
1999
19.
Chakraborti Das, S,
Mondal M,
Roychoudhury S,
and
Chakraborti S.
Oxidants mitochondria and calcium: an overview.
Cell Signal
11:
77-85,
1999[ISI][Medline].
20.
Chance, B,
and
Williams GR.
The respiratory chain and oxidative phosphorylation.
Adv Enzymol Relat Subj
17:
65-134,
1956[ISI].
21.
Chen, YC,
Tsai S-H,
Lin-Shiau S-Y,
and
Lin J-K.
Elevation of apoptotic potential by anoxia-hyperoxia shift in NIH3T3 cells.
Mol Cell Biochem
197:
147-159,
1999[ISI][Medline].
22.
Chihab, R,
Ferry C,
Koziel V,
Monin P,
and
Daval JL.
Sequential activation of activator protein-1 related transcription factors and JNK protein kinases may contribute to apoptotic death induced by transient hypoxia in developing brain neurons.
Mol Brain Res
63:
105-120,
1998[ISI][Medline].
23.
Clerici, C,
and
Matthay MA.
Hypoxia regulates gene expression of alveolar epithelial transport proteins.
J Appl Physiol
88:
1890-1896,
2000
24.
Colantoni, A,
de Maria N,
Caraceni P,
Bernardi M,
Floyd RA,
and
Van Thiel DH.
Prevention of reoxygenation injury by sodium salicylate in isolated-perfused rat liver.
Free Radic Biol Med
25:
87-94,
1998[ISI][Medline].
25.
Danielsen, T,
Hvidsten M,
Stokke T,
Solberg K,
and
Rofstad EK.
Hypoxia induces p53 accumulation in the S-phase and accumulation of hypophosphorylated retinoblastoma protein in all cell cycle phases of human melanoma cells.
Br J Cancer
78:
1547-1558,
1998[ISI][Medline].
26.
De Groot, H,
Anundi I,
and
Littauer A.
Hypoxia-reoxygenation injury and the generation of reactive oxygen in isolated hepatocytes.
Biomed Biochim Acta
48:
S11-S15,
1989[ISI][Medline].
27.
De Groot, H,
and
Brecht M.
Reoxygenation injury in rat hepatocytes: Mediation by O2/H2O2 liberated by sources other than xanthine oxidase.
Biol Chem
372:
35-41,
1991.
28.
Delcamp, TJ,
Dales C,
Ralenkotter L,
Cole PS,
and
Hadley RW.
Intramitochondrial [Ca2+] and membrane potential in ventricular myocytes exposed to anoxia-reoxygenation.
Am J Physiol Heart Circ Physiol
275:
H484-H494,
1998
29.
Dong Saikumar, ZP,
Patel Y,
Weinberg JM,
and
Venkatachalam MA.
Serine protease inhibitors suppress cytochrome c-mediated caspase-9 activation and apoptosis during hypoxia-reoxygenation.
Biochem J
347:
669-677,
2000[ISI][Medline].
30.
Du, G,
Mouithys-Mickalad A,
and
Sluse FE.
Generation of superoxide anion by mitochondria and impairment of their functions during anoxia and reoxygenation and reoxygenation in vitro.
Free Radic Biol Med
25:
1066-1074,
1998[ISI][Medline].
31.
Esposti, MD,
Hatzinisiriou I,
McLennan H,
and
Ralph S.
Bcl-2 and mitochondrial oxygen radicals.
J Biol Chem
27:
29831-29837,
1999.
32.
Forfia, PR,
Hintze TH,
Wolin MS,
and
Kaley G.
Role of nitric oxide in the control of mitochondrial function.
Adv Exp Med Biol
471:
381-388,
1999[ISI][Medline].
33.
Fridovich, I.
The biology of oxygen radicals: the superoxide radical is an agent of oxygen toxicity. Superoxide dismutases provide an important defense.
Science
201:
875-880,
1978[ISI][Medline].
34.
Garay, M,
Gaarde W,
Monia BP,
Nero P,
and
Cioffi CL.
Inhibition of hypoxia/reoxygenation-induced apoptosis by an antisense oligonucleotide targeted to JNK1 in human kidney cells.
Biochem Pharmacol
59:
1033-1043,
2000[ISI][Medline].
35.
Gebhardt, BR,
Ries J,
Caspary WF,
Boehles H,
and
Stein J.
Superoxide: a major factor for stress protein induction in reoxygenation injury in the intestinal cell line Caco-2.
Digestion
60:
238-245,
1999[ISI][Medline].
37.
Greene, EL,
and
Paller MS.
Xanthine oxidase produces O
38.
Griffiths, EJ,
Ocampo CJ,
Savage JS,
Rutter GA,
Hansford RG,
Stern MD,
and
Silverman HS.
Mitochondrial calcium transporting pathways during hypoxia and reoxygenation in single rat cardiomyocytes.
Cardiovasc Res
39:
423-433,
1998[ISI][Medline].
39.
Hanson, ES,
and
Leibold EA.
Regulation of iron regulatory protein 1 during hypoxia and hypoxia/reoxygenation.
J Biol Chem
273:
7588-7593,
1998
40.
Hempel, SL,
Haycraft DL,
Hoak JC,
and
Spector AA.
Reduced prostacyclin formation after reoxygenation of anoxic endothelium.
Am J Physiol Cell Physiol
259:
C738-C745,
1990
41.
Hinshaw, DB,
Armstrong BC,
Beals TF,
and
Hyslop PA.
A cellular model of endothelial cell ischemia.
J Surg Res
44:
527-537,
1988[ISI][Medline].
42.
Hohler, B,
Lange B,
Holzapfel B,
Goldenberg A,
Hanze J,
Sell A,
Testan H,
Moller W,
and
Kummer W.
Hypoxic upregulation of tyrosine hydroxylase gene expression is paralleled, but not induced, by increased generation of reactive oxygen species in PC12 cells.
FEBS Lett
457:
53-56,
1999[ISI][Medline].
43.
Horakova, L,
Stolc S,
Chromikova Z,
Pekarova A,
and
Derkova L.
Mechanisms of hippocampal reoxygenation injury. Treatment with antioxidants.
Neuropharmacology
36:
177-184,
1997[ISI][Medline].
44.
Hu, Q,
and
Ziegelstein RC.
Hypoxia/reoxygenation stimulates intracellular calcium oscillations in human aortic endothelial cells.
Circulation
102:
2541-2547,
2000
45.
Huang, YCT,
Fisher PW,
Nozik-Grayck E,
and
Piantadosi CA.
Hypoxia compared with normoxia alters the effects of nitric oxide in ischemia-reperfusion lung injury.
Am J Physiol Lung Cell Mol Physiol
273:
L504-L512,
1997
46.
Irani, K.
Oxidant signaling in vascular cell growth, death, and survival: a review of the roles of oxygen species in smooth muscle and endothelial cell mitogenic and apoptotic signaling.
Circ Res
87:
179-183,
2000
47.
Isowa, N,
Yoshimura T,
Kosaka S,
Liu M,
Hitomi S,
Yodoi J,
and
Wada H.
Human thioredoxin attenuates hypoxia-reoxygenation injury of murine endothelial cells in a thiol-free condition.
J Cell Physiol
183:
33-40,
2000.
48.
Jackson, R,
Parish G,
and
Ho YS.
Effects of hypoxia on expression of superoxide dismutases in cultured ATII cells and lung fibroblasts.
Am J Physiol Lung Cell Mol Physiol
271:
L955-L962,
1996
49.
Jessup, JM,
Battle P,
Waller H,
Edmiston KH,
Stolz DB,
Watkins SC,
Locker J,
and
Skena K.
Reactive nitrogen and oxygen radicals formed during hepatic ischemia-reperfusion kill weakly metastatic colorectal cancer cells.
Cancer Res
59:
1825-1829,
1999
50.
Jovanovic, A,
Jovanovic S,
Carrasco AJ,
and
Terzic A.
Acquired resistance of a mammalian cell line to hypoxia-reoxygenation through cotransfection of Kir6.2 and SUR1 clones.
Lab Invest
78:
1101-1107,
1998[ISI][Medline].
51.
Jung, F,
Palmer LA,
Zhou N,
and
Johns RA.
Hypoxic regulation of inducible nitric oxide synthase via hypoxia inducible factor-1 in cardiac myocytes.
Circ Res
86:
319-325,
2000
52.
Kako, K,
Kato M,
Matsuoka T,
and
Mustapha A.
Depression of membrane-bound Na+-K+-ATPase activity induced by free radicals and by ischemia of kidney.
Am J Physiol Cell Physiol
254:
C330-C337,
1988
53.
Kang, PM,
Haunstetter A,
Aoki H,
Usheva A,
and
Izumo S.
Morphological and molecular characterization of adult cardiomyocyte apoptosis during hypoxia and reoxygenation.
Circ Res
87:
118-125,
2000
54.
Kayyali, U,
Donaldson C,
Huang H,
Abdelnour R,
and
Hassoun P.
Phosphorylation of xanthine dehydrogenase/oxidase in hypoxia.
J Biol Chem
276:
14359-14365,
2001
55.
Killilea, DW,
Hester R,
Balczon R,
Babal P,
and
Gillespie MN.
Free radical production in hypoxic pulmonary artery smooth muscle cells.
Am J Physiol Lung Cell Mol Physiol
279:
L408-L412,
2000
56.
Kim, CD,
Kim YK,
Lee SH,
and
Hong KW.
Rebamipide inhibits neutrophil adhesion to hypoxia/reoxygenation-stimulated endothelial cells via nuclear factor-B-dependent pathway.
J Pharmacol Exp Ther
294:
864-869,
2000
57.
Kim, H,
and
Kim KH.
Role of nitric oxide in oxidative damage in isolated rabbit gastric cells exposed to hypoxia-reoxygenation.
Dig Dis Sci
43:
1042-1049,
1998[ISI][Medline].
58.
Kim, KS,
Takeda K,
Sethi R,
Pracyk JB,
Tanaka K,
Shou YF,
Yu ZX,
Ferrans VJ,
Bruder JT,
Kovesdi I,
Irani K,
Goldschmidt-Clermont P,
and
Finkel T.
Protection from reoxygenation injury by inhibition of rac1.
J Clin Invest
101:
1821-1826,
1998
59.
Kirshenbaum, LA,
and
Singal PK.
Changes in antioxidant enzymes in isolated cardiac myocytes subjected to hypoxia-reoxygenation.
Lab Invest
67:
796-803,
1992[ISI][Medline].
60.
Kirshenbaum, LA,
and
Singal PK.
Antioxidant changes in heart hypertrophy: significance during hypoxia-reoxygenation injury.
Can J Physiol Pharmacol
70:
1330-1335,
1992[ISI][Medline].
61.
Kobayashi, S,
Miescher E,
and
Clemens MG.
A synergistic effect of extracellular hypocalcemic condition for hyperoxic reoxygenation injury in rat hepatocytes.
Transplantation
67:
451-457,
1999[ISI][Medline].
62.
Kowaltowski, AJ,
and
Vercesi AE.
Mitochondrial damage induced by conditions of oxidative stress.
Free Radic Biol Med
26:
463-471,
1999[ISI][Medline].
63.
Krenitsky, TA,
Tuttle JV,
Cattau ED, Jr,
and
Wang P.
A comparison of the distribution and electron acceptor specificities of xanthine oxidase and aldehyde oxidase.
Comp Biochem Physiol B Biochem Mol Biol
49:
687-703,
1974.
64.
Kupatt, C,
Weber C,
Wolf DA,
Becker BF,
Smith TW,
and
Kelly RA.
Nitric oxide attenuates reoxygenation-induced ICAM-1 expression in coronary microvascular endothelium: Role of NF-B.
J Mol Cell Cardiol
29:
2599-2609,
1997[ISI][Medline].
65.
Laderoute, KR,
and
Webster KA.
Hypoxia/reoxygenation stimulated Jun kinase activity through redox signaling in cardiac myocytes.
Circ Res
80:
336-344,
1997
66.
Leo, R,
Pratico D,
Iuliano L,
Pulcinelli FM,
Ghiselli A,
Pignatelli P,
Colavita AR,
FitzGerald GA,
and
Violi F.
Platelet activation by superoxide anion and hydroxyl radicals intrinsically generated by platelets that had undergone anoxia and then reoxygenation.
Circulation
95:
885-891,
1997
67.
Levinson, RM,
Shure D,
and
Moser KM.
Reperfusion pulmonary edema after pulmonary artery thromboendarterectory.
Am Rev Respir Dis
134:
1241-1245,
1986[ISI][Medline].
68.
Levy, R,
Smith SD,
Chandler K,
Sadovsky Y,
and
Nelson DM.
Apoptosis in human cultured trophoblasts is enhanced by hypoxia and diminished by epidermal growth factor.
Am J Physiol Cell Physiol
278:
C982-C988,
2000
69.
Li C, Wright M, and Jackson R. Reactive species-mediated lung
epithelial cell death after hypoxia and reoxygenation. Exp Lung
Res. In press.
70.
Li, D,
Tomson K,
Yang B,
Mehta P,
Croker BP,
and
Mehta JL.
Modulation of constitutive nitric oxide synthase, bcl-2 and Fas expression in cultured human coronary endothelial cells exposed to anoxia-reoxygenation and angiotensin II: role of AT1 receptor activation.
Cardiovasc Res
41:
109-115,
1999[ISI][Medline].
71.
Lum, H,
Barr DA,
Shaffer JR,
Gordon RJ,
Ezrin AM,
and
Malik AB.
Reoxygenation of endothelial cells increases permeability by oxidant-dependent mechanisms.
Circ Res
70:
991-998,
1992[Abstract].
72.
Macmillan-Crow, LA,
Crow JP,
Kerby JD,
Beckman JS,
and
Thompson JA.
Nitration and inactivation of manganese superoxide dismutase in chronic rejection of human renal allografts.
Proc Natl Acad Sci USA
93:
11853-11858,
1996
73.
Mairbaurl, H,
Wodopia R,
Eckes S,
Schulz S,
and
Bartsch P.
Impairment of cation transport in A549 cells and rat alveolar epithelial cells by hypoxia.
Am J Physiol Lung Cell Mol Physiol
273:
L797-L806,
1997[ISI][Medline].
74.
Matalon, S,
Benos D,
and
Jackson RM.
Biophysical and molecular properties of amiloride-inhibitable Na+ channels in alveolar epithelial cells.
Am J Physiol Lung Cell Mol Physiol
271:
L1-L22,
1996
75.
Matsushita, H,
Morishita R,
Nata T,
Aoki M,
Nakagami H,
Taniyama Y,
Yamamoto K,
Higaki J,
Yasufumi K,
and
Ogihara T.
Hypoxia-induced endothelial apoptosis through nuclear factor-B (NF-
B)-mediated bcl-2 suppression: in vivo evidence of the importance of NF-
B in endothelial cell regulation.
Circ Res
86:
974-981,
2000
76.
McCord, JM.
Oxygen-derived free radicals in postischemic tissue injury.
N Engl J Med
312:
159-163,
1985[Abstract].
77.
McGowan, AJ,
Ruiz-Ruiz MC,
Gorman AM,
Lopez-Rivas A,
and
Cotter TG.
Reactive oxygen intermediate(s) (ROI): common mediator(s) of poly(ADP-ribose) polymerase (PARP) cleavage and apoptosis.
FEBS Lett
392:
299-303,
1996[ISI][Medline].
78.
McLeod, L,
and
Alayash AI.
Detection of a ferrylhemoglobin intermediate in an endothelial cell model after hypoxia-reoxygenation.
Am J Physiol Heart Circ Physiol
277:
H02-H99,
1999.
79.
Mizukami, Y,
Kobayashi S,
Uberall F,
Hellbert K,
Kobayashi N,
and
Yoshida KI.
Nuclear mitogen-activated protein kinase activation by protein kinase C during reoxygenation after ischemic hypoxia.
J Biol Chem
275:
19921-19927,
2000
80.
Mizukami, Y,
Yoshioka K,
Morimoto S,
and
Yoshida KI.
A novel mechanism of JNK1 activation.
J Biol Chem
272:
16657-16662,
1997
81.
Murphy, BJ,
Robin ED,
Tapper DP,
Wong RJ,
and
Clayton DA.
Hypoxic coordinate regulation of mitochondrial enzymes in mammalian cells.
Science
223:
707-709,
1984[ISI][Medline].
82.
Muxfelt, M,
and
Schaper W.
The activity of xanthine oxidase in heart of pigs, guinea pigs, rabbits, rats, and humans.
Basic Res Cardiol
82:
486-492,
1987[ISI][Medline].
83.
Nakano, M,
Mann DL,
and
Knowlton AA.
Blocking the endogenous increase in HSP 72 increases susceptibility to hypoxia and reoxygenation in isolated adult feline cardiocytes.
Circulation
95:
1523-1531,
1997
84.
Nemoto, S,
Takeda K,
Yu ZX,
Ferrans VJ,
and
Finkel T.
Role of mitochondrial oxidants as regulators of cellular metabolism.
Mol Cell Biol
20:
7311-7314,
2000
85.
Ohman, T,
Parish G,
and
Jackson RM.
Hypoxic modulation of manganese superoxide dismutase promoter activity and gene expression in lung epithelial cells.
Am J Respir Cell Mol Biol
21:
119-127,
1999
86.
Ozaki, M,
Deshpande SS,
Angkeow P,
Bellan J,
Lowenstein CJ,
Dinauer MC,
Goldschmidt-Clermont PJ,
and
Irani K.
Inhibition of the Rac1 GTPase protects against nonlethal ischemia/reperfusion-induced necrosis and apoptosis in vivo.
FASEB J
14:
418-429,
2000
87.
Ozaki, M,
Deshpande SS,
Angkeow P,
Suzuki S,
and
Irani K.
Rac1 regulates stress-induced, redox-dependent heat shock factor activation.
J Biol Chem
275:
35377-35383,
2000
88.
Paller, MS.
Lateral diffusion of lipids in renal cells: effects of hypoxia and reoxygenation and role of cytoskeleton.
Am J Physiol Cell Physiol
264:
C201-C208,
1993
89.
Paller, MS,
and
Neumann TV.
Reactive oxygen species and rat renal epithelial cells during hypoxia and reoxygenation.
Kidney Int
40:
1041-1049,
1991[ISI][Medline].
90.
Park, JH,
Okayama N,
Gute D,
Krsmanovic A,
Battarbee H,
and
Alexander JS.
Hypoxia/aglycemia increases endothelial permeability: role of second messengers and cytoskeleton.
Am J Physiol Cell Physiol
277:
C1066-C1074,
1999
91.
Parks, DA,
and
Granger DN.
Xanthine oxidase: biochemistry, distribution and physiology.
Acta Physiol Scand
548, Suppl:
87-99,
1986.
92.
Pastorino, JG,
Snyder JW,
Hoek JB,
and
Farber JL.
Ca2+ depletion prevents anoxic death of hepatocytes by inhibiting mitochondrial permeability transition.
Am J Physiol Cell Physiol
268:
C676-C685,
1995
93.
Pitkanen, S,
and
Robinson BH.
Mitochondrial complex I deficiency leads to increased production of superoxide radicals and induction of superoxide dismutase.
J Clin Invest
98:
345-351,
1996
94.
Plateel, M,
Dehouck MP,
Torpier G,
Cecchelli R,
and
Teissier E.
Hypoxia increases the susceptibility to oxidant stress and the permeability of the blood-brain barrier endothelial cell monolayer.
J Neurochem
65:
2138-2145,
1995[ISI][Medline].
95.
Poderoso, JJ,
Lisedero C,
Schopfer F,
Riobo N,
Carreras MC,
Cadenas E,
and
Boveris A.
The regulation of mitochondrial oxygen uptake by redox reactions involving nitric oxide and ubiquinol.
J Biol Chem
274:
37709-33716,
1999
96.
Poderoso, JJ,
Peralta JG,
Lisdero CL,
Carreras MC,
Radisic M,
Schopfer F,
Cadenas E,
and
Boveris A.
Nitric oxide regulates uptake and hydrogen peroxide release by the isolated beating rat heart.
Am J Physiol Cell Physiol
274:
C112-C119,
1998
97.
Raha, S,
McEachern GE,
Myint AT,
and
Robinson BH.
Superoxides from mitochondrial complex III: the role of manganese superoxide dismutase.
Free Radic Biol Med
29:
170-180,
2000[ISI][Medline].
98.
Rakhit, RD,
Edwards RJ,
Mockridge JW,
Baydoun AR,
Wyatt AW,
Mann GE,
and
Marber MS.
Nitric oxide-induced cardioprotection in cultured rat ventricular myocytes.
Am J Physiol Heart Circ Physiol
278:
H1211-H1217,
2000
99.
Ratych, RE,
Chuknyiska RS,
and
Bulkley GB.
The primary localization of free radical generation after anoxia/reoxygenation in isolated endothelial cells.
Surgery
102:
122-131,
1987[ISI][Medline].
100.
Reinheckel, T,
Korn S,
Mohring S,
Augustin W,
Halangk W,
and
Schild L.
Adaptation of protein carbonyl detection to the requirements of proteome analysis demonstrated for hypoxia/reoxygenation in isolated rat liver mitochondria.
Arch Biochem Biophys
376:
59-65,
2000[ISI][Medline].
101.
Robin, ED,
Murphy BJ,
and
Theodore J.
Coordinate regulation of glycolysis by hypoxia in mammalian cells.
J Cell Physiol
118:
287-290,
1984[ISI][Medline].
102.
Robin, ED,
and
Theodore J.
Are there ischemic lung diseases?
Arch Intern Med
142:
1791-1792,
1982[ISI][Medline].
103.
Russell, W,
Matalon S,
and
Jackson R.
MnSOD expression in alveolar epithelial cells from hypoxic and hypoperfused lungs.
Am J Respir Cell Mol Biol
11:
366-371,
1994[Abstract].
104.
Saikumar, P,
Dong Z,
Patel Y,
Hall K,
Hopfer U,
Weinberg JM,
and
Venkatachalam MA.
Role of hypoxia-induced bax translocation and cytochrome c release in reoxygenation.
Oncogene
17:
3401-3415,
1998[ISI][Medline].
105.
Saikumar, P,
Dong Z,
Weinberg JM,
and
Venkatachalam MA.
Mechanisms of cell death in hypoxia/reoxygenation injury.
Oncogene
17:
3341-3349,
1998[ISI][Medline].
106.
Sakamoto, K,
Urushidani T,
and
Nagao T.
Translocation of HSP27 to cytoskeleton by repetitive hypoxia-reoxygenation in the rat myoblast cell line, H9c2.
Biochem Biophys Res Commun
251:
576-579,
1998[ISI][Medline].
107.
Schafer, C,
Ladilov YV,
Siegmund B,
and
Piper HM.
Importance of bicarbonate transport for protection of cardiomyocytes against reoxygenation injury.
Am J Physiol Heart Circ Physiol
278:
H1457-H1463,
2000
108.
Schinetti, ML,
Sbarbati R,
and
Scarlattini M.
Superoxide production by human umbilical vein endothelial cells in an anoxia-reoxygenation model.
Cardiovasc Res
23:
76-80,
1989[ISI][Medline].
109.
Semenza, GL.
HIF-1: mediator of physiological and pathophysiological responses to hypoxia.
J Appl Physiol
88:
1474-1480,
2000
110.
Semenza, GL.
Cellular and molecular dissection of reperfusion injury ROS within and without.
Circ Res
86:
117-118,
2000
111.
Sharpe, MA,
and
Cooper CE.
Interaction of peroxynitrite with mitochondrial cytochrome oxidase.
J Biol Chem
273:
30961-30972,
1998
112.
Shlafer, M,
Myers CL,
and
Adkins S.
Mitochondrial hydrogen peroxide generation and activities of glutathione peroxidase and superoxide dismutase following global ischemia.
J Mol Cell Cardiol
19:
1195-1206,
1987[ISI][Medline].
113.
Simon, LM,
Robin ED,
Phillips JR,
Acevedo J,
Axline SG,
and
Theodore J.
Enzymatic basis for bioenergetic differences of alveolar versus peritoneal macrophages and enzyme regulation by molecular O2.
J Clin Invest
59:
443-448,
1977[ISI][Medline].
114.
Soboll, S,
Brdiczka D,
Jahnke D,
Schmidt A,
Schlattner U,
Wendt S,
Wyss M,
and
Wallimann T.
Octomer-dimer transitions of mitochondrial creatine kinase in heart disease.
J Mol Cell Cardiol
31:
857-866,
1999[ISI][Medline].
115.
Suzuki, K,
Sawa Y,
Kaneda Y,
Ichikawa H,
Shirakura R,
and
Matsuda H.
Over expressed heat shock protein 70 attenuates hypoxic injury in coronary endothelial cells.
J Mol Cell Cardiol
30:
1129-1136,
1998[ISI][Medline].
116.
Tagami, M,
Yamagata K,
Ikeda K,
Nara Y,
Fujino H,
Kubota A,
Numano F,
and
Yamori Y.
Vitamin E prevents apoptosis in cortical neurons during hypoxia and oxygen reperfusion.
Lab Invest
78:
1415-1429,
1998[ISI][Medline].
117.
Tan, S,
Zhou F,
Nielsen VG,
Wang Z,
Gladson CL,
and
Parks DA.
Increased injury following intermittent fetal hypoxia-reoxygenation is associated with increased free radical production in fetal rabbit brain.
J Neuropathol Exp Neurol
58:
972-981,
1999[ISI][Medline].
118.
Terada, LS.
Hypoxia-reoxygenation increases O2 efflux, which injures endothelial cells by an extracellular mechanism.
Am J Physiol Heart Circ Physiol
270:
H945-H950,
1996
119.
Thannickal, VJ,
and
Fanburg BL.
Reactive oxygen species in cell signaling.
Am J Physiol Lung Cell Mol Physiol
279:
L1005-L1028,
2000
120.
Tong, WH,
and
Rouault T.
Distinct iron-sulfur cluster assembly complexes exist in the cytosol and mitochondria of human cells.
EMBO J
19:
5692-5700,
2000
121.
Valdez, LB,
Alvarez S,
Arnaz SL,
Schopfer F,
Carreras MC,
Poderoso JJ,
and
Boveris A.
Reactions of peroxynitrite in the mitochondrial matrix.
Free Radic Biol Med
29:
349-356,
2000[ISI][Medline].
122.
Van der Vliet, A,
Eiserich JP,
Halliwell B,
and
Cross CE.
Formation of reactive nitrogen species during peroxidase-catalyzed oxidation of nitrite.
J Biol Chem
272:
7617-7625,
1997
123.
Vogt, M,
Bauer MKA,
Ferrari D,
and
Schulze-Osthoff K.
Oxidative stress and hypoxia/reoxygenation trigger CD95 (APO-1/Fas) ligand expression in microglial cells.
FEBS Lett
429:
67-72,
1998[ISI][Medline].
124.
Waleh, NS,
Calaoagan J,
Murphy BJ,
Knapp AM,
Sutherland RM,
and
Laderoute KR.
The redox-sensitive human antioxidant responsive element induces gene expression under low oxygen conditions.
Carcinogenesis
19:
1333-1337,
1998[Abstract].
125.
Wang, GL,
Jiang BH,
Rue EA,
and
Semenza GL.
Hypoxia inducible factor 1 is a basic-helix-loop-helix-PAS heterodimer regulated by cellular O2 tension.
Proc Natl Acad Sci USA
92:
5510-5514,
1995[Abstract].
126.
Watkins, MT,
Al-Badawi H,
Cardenas R,
Dubois E,
and
Larson DM.
Endogenous reactive oxygen metabolites mediate sublethal endothelial cell dysfunction during reoxygenation.
J Vasc Surg
23:
95-103,
1996[ISI][Medline].
127.
Watkins, MT,
Haudenschild CC,
Al-Badawi H,
Velazquez FR,
and
Larson DM.
Immediate responses of endothelial cells to hypoxia and reoxygenation: An in vitro model of cellular dysfunction.
Am J Physiol Heart Circ Physiol
268:
H749-H758,
1995
128.
Webster, KA,
Disher DJ,
Kaiser S,
Hernandez O,
Sato B,
and
Bishopric NH.
Hypoxia-activated apoptosis of cardiac myocytes requires reoxygenation or a pH shift and is independent of p53.
J Clin Invest
104:
239-252,
1999
129.
Wei, Z,
Costa K,
Al-Mehdi AB,
Dodia C,
Muzyantov V,
and
Fisher AB.
Simulated ischemia in flow-adapted endothelial cells leads to generation of reactive oxygen species in cell signaling.
Circ Res
85:
682-689,
1999
130.
Weinberg, JM,
Venkatachalam MA,
Roeser NF,
and
Nissim I.
Mitochondrial dysfunction during hypoxia/reoxygenation and its correction by anaerobic metabolism of citric acid cycle intermediates.
Proc Natl Acad Sci USA
97:
2826-2831,
2000
131.
Weinberg, JM,
Venkatachalam MA,
Roeser NF,
Saikumar P,
Dong Z,
Senter RA,
and
Nissim I.
Anaerobic and aerobic pathways for salvage of proximal tubules from hypoxia-induced mitochondrial injury.
Am J Physiol Renal Physiol
279:
F927-F943,
2000
132.
Whitmarsh, AJ,
and
Davis RJ.
Transcription factor AP-1 regulation by mitogen-activated protein kinase signal transduction pathways.
J Mol Med
74:
589-607,
1996[ISI][Medline].
133.
Yao, Z,
Tong J,
Tan X,
Li CQ,
Shao A,
Kin WC.,
Vanden Hoek TL,
Becker LB,
Head CA,
and
Schumacker PT.
Role of reactive oxygen species in acetylcholine-induced preconditioning in cardiomyocytes.
Am J Physiol Heart Circ Physiol
277:
H2504-H2509,
1999
134.
Zou, MH,
and
Bachschmid M.
Hypoxia-reoxygenation triggers coronary vasospasm in isolated bovine coronary arteries via tyrosine nitration of prostacyclin synthase.
J Exp Med
190:
135-139,
1999
135.
Zweier, JL,
Kuppusamy P,
Thompson-Gorman S,
Klunk D,
and
Lutty GA.
Measurement and characterization of free radical generation in reoxygenated human endothelial cells.
Am J Physiol Cell Physiol
266:
C700-C708,
1994