Department of Physiology, University of Tübingen, D-72076 Tübingen, Germany
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Abstract |
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Osmotic cell swelling activates Cl channels
to achieve anion efflux. In this study, we find that both
the tyrosine kinase inhibitor herbimycin A and genetic
knockout of p56lck, a src-like tyrosine kinase, block regulatory volume decrease (RVD) in a human T cell line.
Activation of a swelling-activated chloride current
(ICl
swell) by osmotic swelling in whole-cell patch-clamp
experiments is blocked by herbimycin A and lavendustin. Osmotic activation of ICl
swell is defective in p56lck-deficient cells. Retransfection of p56lck restores osmotic
current activation. Furthermore, tyrosine kinase activity is sufficient for activation of ICl
swell. Addition of purified p56lck to excised patches activates an outwardly
rectifying chloride channel with 31 pS unitary conductance. Purified p56lck washed into the cytoplasm activates ICl
swell in native and p56lck-deficient cells even
when hypotonic intracellular solutions lead to cell
shrinkage. When whole-cell currents are activated either by swelling or by p56lck, slow single-channel gating
events can be observed revealing a unitary conductance
of 25-28 pS. In accordance with our patch-clamp data,
osmotic swelling increases activity of immunoprecipitated p56lck. We conclude that osmotic swelling activates ICl
swell in lymphocytes via the tyrosine kinase
p56lck.
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Introduction |
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WHEN cells are exposed to hypotonic stress, initial
swelling is followed by regulatory volume decrease (RVD).1 In lymphocytes, RVD involves
activation of volume-sensitive anion channels, leading to
membrane depolarization and thereby opening voltage-activated potassium channels (Deutsch and Lee, 1988). This produces a net loss of KCl, resulting in regulatory decrease of intracellular osmolarity and driving H2O out of
the cell. Anion channels activated by osmotic stress are expressed in a wide variety of nonexcitable and excitable tissues (for review see Lang et al., 1997), and are thought to
mediate an efflux of osmotically active anions in response
to increased cellular volume (Cahalan and Lewis, 1988
).
Biophysical and pharmacological differences have been
observed between swelling-activated anion channels found
in lymphocytes and other tissues (Kunzelmann et al., 1989;
Solc and Wine, 1991; Sorota, 1992
; Lewis et al., 1993
).
Most of these channels are outwardly rectifying and possess unitary conductances ranging from 20 to 90 pS. At
least three different anion channels have been characterized at the single channel level in membrane patches from
lymphocytes (Lewis and Cahalan, 1988
; Nishimoto et al.,
1991
; Garber, 1992
). However, a clear relationship between single-channel currents and whole-cell currents is
lacking. Although the genes for a number of different Cl
channel proteins have been cloned, the proteins forming
swelling activated anion channels in lymphocytes have not
yet been identified. Their activation mechanism is even
less completely understood. In lymphocytes, neither an increase in cytosolic calcium nor in membrane area is necessary for activation of volume-sensitive anion channels
(Ross et al., 1994
; Ross and Cahalan, 1995
). However, participation of cytoskeletal elements in channel activation
has been demonstrated (Levitan et al., 1995
). Most interestingly, the presence of intracellular ATP is necessary for
maintenance or repeated activation of the swelling-activated anion current (Lewis et al., 1993
; Ross et al., 1994
).
Recent work has shown inhibition of volume-sensitive
chloride current in heart cells by tyrosine-kinase inhibitors
(Sorota, 1995
) and regulation of the cystic fibrosis transmembrane conductance regulator (CFTR) channel by tyrosine phosphorylation (Fischer and Machen, 1996
). In
this study we have examined the role of a src-like lymphocyte tyrosine kinase, p56lck, in the activation of swelling-
activated anion channels in lymphocytes.
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Materials and Methods |
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Cell Culture and Stimulation
Jurkat and p56lck-deficient JCaM1.6 cells were obtained from the American Type Culture Collection (Rockville, MD), p56lck reconstituted
JCaM1.6 (JCaM1.6/Lck+) were a gift from Dr. A. Weiss (University of
California, San Francisco, CA). The cells were grown in RPMI-1640 medium supplemented with 10% FCS, 10 mM Hepes, pH 7.4, 2 mM
L-glutamine, 1 mM sodium pyruvate, 100 µM nonessential amino acids,
100 U/ml penicillin, 100 µg/ml streptomycin (all purchased from Life
Technologies, Eggenstein, Germany), and 50 µM -mercaptoethanol.
JCaM1.6/Lck+ were cultured in 250 µg/ml hygromycin, which was removed 48-72 h before beginning of experiments. Stable expression of
p56lck was verified (data not shown). The specific src-like tyrosine kinase
inhibitor herbimycin A (Calbiochem, Bad Soden, Germany) was added to
the cells at a concentration of 10 µM 7-8 h before the experiments.
Solutions
Cells were superfused with modified Ringer's containing 145 mM NaCl,
5 mM KCl, 2 mM CaCl2, 1 mM MgCl2, 10 mM glucose, and 10 mM Hepes,
pH 7.4 (310 mOsmol/kg). The internal pipette solution was used to separate Cl currents in lymphocytes (Ross et al., 1994
) and contained 160 Cs+-glutamate, 0.1 mM CaCl2, 2 mM Mg Cl2, 1.1 mM EGTA, 4 mM
Na2ATP, and 10 mM Hepes, pH 7.2 (330 mOsmol/kg). For hypotonic intracellular conditions, this solution was diluted as indicated. For hypertonic conditions, sucrose was added to obtain the indicated osmolality. When varying ATP concentrations, 2 mM Na glutamate replaced 1 mM
Na2ATP, respectively. Purified p56lck was purchased from Upstate Biotechnology Inc. (Lake Placid, NY). All other chemicals were obtained
from Sigma Chemical Co. (Deisenhofen, FRG). Osmolality was measured
using a freezing point osmometer (Knauer, Berlin, FRG).
Volume Measurements
Volume changes were measured on the stage of an inverted microscope (Axiovert 135; Carl Zeiss, Oberkochen, Germany) by video imaging. Cells were loaded with 2 µM calcein-AM (Molecular Probes, Eugene, OR) for 15 min. Excitation was performed at 497 nm using a monochromator (Uhl, Munich, Germany). Video images were recorded at 521 nm and digitized (IMG8; Lindemann and Meiser, Homburg, Germany). The fluorescent cell area was analyzed using the PC version of the public domain NIH Image program (ImagePC; Scion Corp., Frederick, MD; available on the Internet via http://rsb.info.nih.gov/nih-image). Relative volume (V) was calculated from the image area (A) with the following relation:
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Patch-Clamp Recordings
Whole-cell currents were recorded at 31°C using an EPC-9 patch-clamp
amplifier and Pulse software (Heka, Lambrecht, Germany). Experiments
were performed on an Axiovert 135 microscope and cells were observed
using a video system to note volume changes. Pipettes were pulled to a resistance of 2-5 M from borosilicate glass. For high resolution recordings,
pipettes were coated with sylgard (Dow Corning, Midland, MI). Capacitive transients were cancelled using the Cslow-compensation of the amplifier. Series resistance was not compensated. Cells were held at 0 mV and
voltage ramps or pulses of the indicated size were applied every 5 or 20 s. The current signal was filtered at 1 kHz and digitized at a 5-kHz sampling
rate. By convention, anionic inward fluxes are shown as positive (outward) currents.
Immunoprecipitation and p56lck Assay
Cell stimulation was terminated by lysis in 25 mM Hepes, pH 7.4, 0.1%
SDS, 0.5% sodium deoxycholate, 1% Triton X-100, 125 mM NaCl, 10 mM
of each sodium fluoride, Na3VO4, and sodium pyrophosphate and 10 µg/ml
of each aprotinin and leupeptin (radioimmunoprecipitation assay buffer)
for immunoprecipitation of p56lck. After lysis, DNA and cell debris were
pelleted by centrifugation at 20,000 g for 15 min, and the supernatants
were subjected to immunoprecipitation of p56lck using an anti-p56lck polyclonal antibody (Upstate Biotechnology Inc.). Control immunoprecipitates were performed with irrelevant affinity-purified polyclonal rabbit immunoglobulins. Immunoprecipitates were incubated overnight at 4°C.
After addition of anti-rabbit, IgG-coupled agarose, incubation was continued for at least 60 min. Immunocomplexes were washed four times in
lysis buffer, twice in kinase buffer (25 mM Hepes, pH 7.0, 150 mM NaCl,
10 mM MnCl2, 1 mM Na3VO4, 5 mM DTT, and 0.5% NP-40), and then resuspended in the same buffer. The kinase reaction was initiated by addition of 10 µCi [32P]ATP (3,000 Ci/mmol; Du Pont-NEN, Boston, MA)
and ATP (10 µM) in kinase buffer. The samples were incubated at 30°C
for 20 min, the reaction was stopped with reducing 5× SDS sample buffer
and 10% SDS-PAGE was performed, followed by autoradiography. An
aliquot of the immunoprecipitates was analyzed by immunoblotting for
detection of equal amounts of p56lck. Immunoblots were developed by incubation with HRP-conjugated protein G (BIO RAD Laboratories,
München, Germany) and a chemiluminescence kit (Amersham, Braunschweig, Germany).
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Results |
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RVD Depends on Tyrosine Kinase Activity
When Jurkat T lymphocytes were superfused with 80% Ringer's (250 mOsmol/kg), RVD restored the initial volume after 13 min in control cells (Fig. 1). RVD was completely blocked in cells preincubated with 10 µM herbimycin A and was defective in JCaM1.6 cells, a Jurkat subclone deficient for the src-like tyrosine kinase p56lck. Retransfection of p56lck restored RVD in JCaM1.6 cells. To elucidate the mechanism of RVD block by inhibition of src-like tyrosine kinases, we studied the volume-sensitive anion current with the patch-clamp method.
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Osmotic Activation of a Chloride Current (ICl) Requires a Tyrosine Kinase
Osmotic swelling of Jurkat T cells induced a Cl current
10-20 s after washing a hypertonic pipette solution into the
cell. The current was characterized by strong outward rectification and a poor permeability to intracellular glutamate
(Fig. 2 A). The swelling-activated Cl
current (ICl
swell) did
not undergo visible inactivation using 200-ms pulses up to
80 mV, and was blocked by 500 µM diisothiocyanato-2-2-stilbenesulfonic acid (DIDS), as previously described (Lewis et
al., 1993
).
|
In contrast, the development of the outwardly rectifying
current was attenuated and delayed in JCaM1.6 cells. Osmotic activation of the current was rescued in JCaM1.6/
lck+ cells retransfected with p56lck. Furthermore, IClswell
was blocked in Jurkat cells by the inhibitors of src-like tyrosine kinases herbimycin A and lavendustin. The time
course of outward currents is summarized in Fig. 2 B. Table I shows dose-dependent block by lavendustin (IC50
10 nM) and compares outward currents using different genetic and pharmacological manipulations.
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p56lck Activates Chloride Conductance without Swelling
If tyrosine phosphorylation is a crucial step in the activation of IClswell, addition of constitutively active p56lck to
the cytosol should activate ICl
swell in the native as well as
the lck-deficient cell line without cell swelling. When using
a hypotonic pipette solution (260 mOsmol/kg), Jurkat cells
started to shrink shortly after break-in. However, a large ICl could be observed when purified p56lck was added to
the intracellular solution (Table I). This current shared
with the swelling-activated conductance strong outward rectification, a poor permeability to glutamate and lack of
inactivation (Fig. 3, A and B). Because Jurkat cells possess
intrinsic p56lck activity, we attempted to activate ICl in the
p56lck-deficient subclone JCaM1.6 using hypotonic pipette
solutions. In five whole-cell recordings from JCaM1.6 cells
patched with a slightly hypotonic pipette solution (300 mOsmol/kg) ICl did not activate and cell volume decreased
slowly during the experiment. However, when p56lck was
added to the pipette solution, a small outwardly rectifying ICl developed (Fig. 3 C; Table I). The current was completely and reversibly blocked by 500 µM DIDS (Fig. 3 C)
and no fast inactivation could be observed (data not
shown). Thus, purified lck activates ICl with properties indistinguishable from ICl
swell.
|
p56lck Activates Cl Channels in Excised Patches
Addition of purified p56lck to the cytosolic surface of excised patches from Jurkat T cells activated an outwardly
rectifying Cl channel (Fig. 4, A and B). No spontaneous
activation was observed in 55 excised patches held at 0 mV
holding potential without enzyme added. The channel
showed outward rectification, even with symmetrical Cl
concentrations, and was selective for Cl
over glutamate
(Fig. 4 D).
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Single-Channel Transitions in Whole-Cell Recordings
Single-channel opening and closing transitions between
discrete whole-cell current levels were frequently seen,
when ICl was slowly activated by p56lck in JCaM1.6 cells using slightly hypotonic intracellular solution (300 mOsmol/kg;
Fig. 3 C). Single-channel openings lasting for several seconds were observed in continuous recordings at constant voltage (Fig. 4 C). The transitions in current traces obtained with voltage ramps frequently spanned more than
one channel level. A similar behavior has been described
for swelling-activated chloride channels (Meyer and Korbmacher, 1996). With voltage ramps, the current often
jumped several times between an open and closed state.
Single-channel transitions could also be observed when
Jurkat cells were patched with slightly hypertonic intracellular solution (330 mOsmol/kg). Cell volume increased
and IClswell activated slowly under these conditions. Transitions in whole-cell currents either activated by p56lck or
by slow swelling are compared with single-channel transitions from excised, p56lck-activated patches in Fig. 4 D.
We obtained unitary conductances of 25, 28, and 31 pS at
40 mV when constructing IV plots from single-channel
transitions activated by swelling or purified p56lck in
whole-cell recordings, or activated by p56lck in excised
patches, respectively.
Osmotic Cell Swelling Activates p56lck
To measure p56lck kinase activity, Jurkat T cells were exposed to hypotonic extracellular solution (250 mOsmol/kg) and in vitro assays were performed on immunoprecipitated p56lck. A transient increase in p56lck activity was observed resembling the time course of RVD. p56lck activation was detected 1 min after exposure to osmotic stress, peaked at 15 min, and then declined rapidly thereafter (Fig. 5). No activation of p56lck was seen when cells were kept in isotonic solution (data not shown).
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Discussion |
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In this study, we show for the first time that the tyrosine
kinase, p56lck, mediates RVD by activating IClswell. T cells
deficient for p56lck are defective in RVD and activation of
ICl
swell, and retransfection of this kinase results in restoration of osmotic current activation.
Several observations suggesting involvement of a phosphorylation event in osmotic current activation have been
reported. ATP in the pipette is required for maintenance
and repeated activation of IClswell in lymphocytes (Lewis
et al., 1993
; Ross and Cahalan, 1995
). A similar ATP dependence has been demonstrated in many different endothelial and epithelial cell types (Gill et al., 1992
; Jackson et al.,
1994
, 1996
; Oiki et al., 1994
; Meyer and Korbmacher,
1996
), although some discrepancies exist between different cells, i.e., the ability of nonhydrolyzable ATP analogues to replace ATP. Furthermore, a delay between the volume
change and current activation in the range of 1 min is typically observed, making a direct link between membrane
stretch and channel gating unlikely (Lewis et al., 1993
; Ross
et al., 1994
). Direct evidence for involvement of tyrosine
phosphorylation in ICl
activation came from pharmacological studies. Inhibitors of tyrosine phosphorylation have
been recently reported to inhibit swelling-induced 125I efflux in intestinal epithelium (Tilly et al., 1993
) and activation of ICl in cardiac and endothelial cells (Sorota, 1995
;
Voets et al., 1998
). To our knowledge, no specific tyrosine
kinase has been linked to the activation of ICl
swell so far.
When compared with the native Jurkat cell line, activation of IClswell in JCaM1.6 cells was not completely abolished, but reduced in size and delayed. This could conceivably indicate a permissive role for p56lck-mediated tyrosine
phosphorylation. However, the p56lck-deficient cell line
JCaM1.6 expresses other src-like kinases like fyn (August
and Dupont, 1995
). Herbimycin A and lavendustin, which
inhibit all src-like kinases, blocked RVD and the osmotic current response. Therefore, we suppose that other src-like kinases can partially substitute for lck in lck-deficient
cells. Strong evidence for a crucial role of p56lck comes
from the experiments using purified p56lck. When added to
the cytosol, p56lck activates a whole-cell chloride current
with properties indistinguishable from ICl
swell without cell
swelling and opens a Cl
channel in excised patches. Both
currents share lack of inactivation, block by 500 µM
DIDS, selectivity for Cl
, and outward rectification. The
smaller amplitude of the lck-activated current typically observed in JCaM1.6 cells could be attributed to amplification of kinase activity by phosphorylation of the native
p56lck present in Jurkat cells.
Several reports show that CFTR can be involved in the
regulation of outwardly rectifying chloride channels (Gabriel et al., 1993; Schwiebert et al., 1995
). Single-channel recordings from fibroblasts transfected with CFTR have revealed the activation of a fast gate by the tyrosine kinase
p60c-src, increasing this chloride channel's open probability
(Fischer and Machen, 1996
). Whereas ICl
swell is easily distinguishable from CFTR channels by its outward rectification and sensitivity to DIDS, the CFTR protein could represent a target for tyrosine phosphorylation, regulating the
ICl
swell studied here. Identification, cloning, and purification of the channel protein underlying ICl
swell in lymphocytes will be necessary to determine the phosphorylation
target. Therefore, we attempted to characterize the single
channel underlying ICl
swell in whole-cell recordings.
The single channel responsible for IClswell has not been
identified so far. An outwardly rectifying, DIDS-sensitive 40-50 pS chloride channel can be activated by membrane
excision from lymphocytes and prolonged depolarization
(Garber, 1992
). However, ~1 pS unitary conductance was
estimated by stationary noise analysis of ICl
swell in lymphocytes (Doroshenko and Neher, 1992
; Lewis et al.,
1993
). A solution to this discrepancy could come from the
observation, that ICl
swell channels in epithelial cells show
prolonged open states with minimal channel gating (Jackson and Strange, 1995
; Meyer and Korbmacher, 1996
). When current variance is analyzed to obtain information
about unitary events, gating events could be missed because of their low frequency. Recording at room temperature further slows down gating kinetics and the lack of
voltage-dependent inactivation hinders the use of nonstationary noise analysis. In the present study we observed
single-channel events in high resolution whole-cell recordings. The channels show extremely slow gating even at
31°C and prolonged open states lasting for several seconds. Similar behavior of swelling-activated chloride channels has been recently described in glioma and kidney
epithelial cells (Jackson and Strange, 1995
; Meyer and
Korbmacher, 1996
). We obtain unitary conductances of 25 and 28 pS when constructing IV plots from single channel transitions in whole-cell recordings activated by swelling
and by purified p56lck, respectively. Furthermore, we were
able to activate a 31-pS, outwardly rectifying Cl
channel
in excised membrane patches by adding purified p56lck to
the cytosolic surface. Thus, cell swelling and p56lck seem to
activate the same chloride channel. The 31-pS outwardly rectifying single channels observed in excised patches may
well be responsible for ICl
swell in lymphocytes.
Cell swelling has been previously described to induce tyrosine phosphorylation in an intestinal epithelial cell line
(Tilly et al., 1993). Hypoosmotic stimulation of mitogen-activated protein kinase was blocked by tyrosine kinase inhibitors in astrocytes (Schliess et al., 1996
). Tyrosine kinase activation is upstream of MAP kinase (Schliess et al.,
1996
). In Jurkat T lymphocytes we show for the first time
activation by hypoosmotic cell swelling of a specific tyrosine kinase that is directly involved in the activation of
ICl
swell. Interestingly, the enhanced p56lck activity is transient, following a time course similar to the RVD in intact
lymphocytes (Figs. 1 and 5). Thus, a tight feedback control
seems to regulate volume and p56lck activity. ICl
swell channels are activated by p56lck and mediate volume decrease
by anion efflux, representing an important link in this
novel control loop.
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Footnotes |
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Address all correspondence to Albrecht Lepple-Wienhues, Physiology I, University of Tübingen, Gmelinstrasse 5, D-72076 Tübingen, Germany. Tel.: (49) 7071-2975285. Fax: (49) 7071-293073. E-mail: alepplew{at}uni-tuebingen.de
Received for publication 15 September 1997 and in revised form 2 January 1998.
This work was in part funded by Deutsche Forschungsgemeinschaft Le 792/3-1, La 315/4-3, and Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie/Interdisziplinäres Klinisches Forschungszentrum 01KS9605. I. Szabò is grateful for a European Molecular Biology Organization fellowship. ![]() |
Abbreviations used in this paper |
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RVD, regulatory volume decrease;
ICl, chloride current;
IClswell, swelling-activated chloride current;
CFTR, cystic fibrosis
transmembrane conductance regulator;
DIDS, diisothiocyanato-2-2-stilbenesulfonic acid.
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References |
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---|
1. | August, A., and B. Dupont. 1995. Activation of extracellular signal-regulated protein kinase (ERK/MAP kinase) following CD28 cross-linking: activation in cells lacking p56lck. Tissue Antigens. 46: 155-162 |
2. | Cahalan M.D., and R.S. Lewis. 1988. Role of potassium and chloride channels in volume regulation by T lymphocytes. In Cell Physiology of Blood. R.B. Gunn, and J.C. Parker, editors. Rockefeller University Press, New York. 281-301. |
3. | Deutsch, C., and S.C. Lee. 1988. Cell volume regulation in lymphocytes. Renal Physiol. Biochem. 3: 260-276 . |
4. | Doroshenko, P., and E. Neher. 1992. Volume-sensitive chloride conductance in bovine chromaffin cell membrane. J. Physiol. (Lond.). 449: 197-218 [Abstract]. |
5. | Fischer, H., and T.E. Machen. 1996. The tyrosine kinase p60c-src regulates the fast gate of the cystic fibrosis transmembrane conductance regulator chloride channel. Biophys. J. 71: 3073-3082 [Abstract]. |
6. | Gabriel, S.E., L.L. Clarke, R.C. Boucher, and M.J. Stutts. 1993. CFTR and outward rectifying chloride channels are distinct proteins with a regulatory relationship. Nature. 363: 263-268 |
7. | Garber, S.. 1992. Outwardly rectifying chloride channels in lymphocytes. J. Membr. Biol. 127: 49-56 |
8. | Gill, D.R., S.C. Hyde, C.F. Higgins, M.A. Valverde, G.M. Mintenig, and F.V. Sepulveda. 1992. Separation of drug transport and chloride channel functions of the human multidrug resistance P-glycoprotein. Cell. 71: 23-32 |
9. | Jackson, P.S., and K. Strange. 1995. Single-channel properties of a volume-sensitive anion conductance. Current activation occurs by abrupt switching of closed channels to an open state. J. Gen. Physiol. 105: 643-660 [Abstract]. |
10. | Jackson, P.S., R. Morrison, and K. Strange. 1994. The volume-sensitive organic osmolyte-anion channel VSOAC is regulated by nonhydrolytic ATP binding. Am. J. Physiol. 267: 1203-1209 . |
11. |
Jackson, P.S.,
K. Churchwell,
N. Ballatori,
J.L. Boyer, and
K. Strange.
1996.
Swelling-activated anion conductance in skate hepatocytes: regulation by
cell Cl![]() |
12. | Kunzelman, K., H. Pavenstädt, and R. Greger. 1989. Properties and regulations of chloride channels in cystic fibrosis and normal airway cells. Pflügers. Arch. 415: 172-182 |
13. |
Lang, F.,
G. Busch,
M. Ritter,
H. Völkl,
S. Waldegger,
E. Gulbins, and
D. Häusinger.
1998.
The functional significance of cell volume regulation mechanisms.
Physiol. Rev.
78:
247-306
|
14. |
Levitan, I.,
C. Almonte,
P. Mollard, and
S.S. Garber.
1995.
Modulation of a volume-regulated Cl![]() |
15. | Lewis, R.S., and M.D. Cahalan. 1988. Subset-specific expression of potassium channels in developing murine T lymphocytes. Science 239: 771-775 |
16. | Lewis, R.S., P.E. Ross, and M.D. Cahalan. 1993. Chloride channels activated by osmotic stress in T lymphocytes. J. Gen. Physiol. 101: 801-826 [Abstract]. |
17. | Meyer, K., and C. Korbmacher. 1996. Cell swelling activates ATP-dependent voltage-gated chloride channels in M-1 mouse cortical collecting duct cells. J. Gen. Physiol. 108: 177-193 [Abstract]. |
18. |
Nishimoto, I.,
J.A. Wagner,
H. Schulman, and
P. Gardner.
1991.
Regulation of
Cl![]() |
19. |
Oiki, S.,
M. Kubo, and
Y. Okada.
1994.
Mg2+ and ATP-dependence of volume-sensitive Cl![]() |
20. | Ross, P.E., and M.D. Cahalan. 1995. Ca2+ influx pathways mediated by swelling or stores depletion in mouse thymocytes. J. Gen. Physiol. 106: 415-444 [Abstract]. |
21. | Ross, P.R., S.S. Garber, and M.D. Cahalan. 1994. Membrane chloride conductance and capacitance in Jurkat T lymphocytes during osmotic swelling. Biophys. J. 66: 169-178 [Abstract]. |
22. | Schliess, F., R. Sinning, R. Fischer, C. Schmalenbach, and D. Haussinger. 1996. Calcium-dependent activation of Erk-1 and Erk-2 after hypo-osmotic astrocyte swelling. Biochem. J. 320: 167-171 |
23. | Schwiebert, E.M., M.E. Egan, T.H. Hwang, S.B. Fulmer, S.S. Allen, G.R. Cutting, and W.B. Guggino. 1995. CFTR regulates outwardly rectifying chloride channels through an autocrine mechanism involving ATP. Cell 81: 1063-1073 |
24. |
Solc, C.K., and
J.J. Wine.
1991.
Swelling-induced and depolarization-induced
Cl![]() |
25. | Sorota, S.. 1992. Swelling-induced chloride-sensitive current in canine atrial cells revealed by whole-cell patch-clamp method. Circ. Res. 70: 679-687 [Abstract]. |
26. | Sorota, S.. 1995. Tyrosine protein kinase inhibitors prevent activation of cardiac swelling-induced chloride current. Pflugers Arch. 431: 178-185 |
27. |
Tilly, B.C.,
N. van den Berghe,
L.G. Tertoolen,
M.J. Edixhoven, and
H.R. de
Jonge.
1993.
Protein tyrosine phosphorylation is involved in osmoregulation
of ionic conductances.
J. Biol. Chem.
268:
19919-19922
|
28. |
Voets, T.,
V. Manolopoulos,
J. Eggermont,
C. Ellory,
G. Droogmans, and
B. Nilius.
1998.
Regulation of a swelling-activated chloride current in bovine
endothelium by protein tyrosine phosphorylation and G proteins.
J. Physiol.
506:
341-352
|