Erythrocyte Water Permeability and Renal Function in Double
Knockout Mice Lacking Aquaporin-1 and Aquaporin-3*
Baoxue
Yang,
Tonghui
Ma, and
A. S.
Verkman
From the Departments of Medicine and Physiology, Cardiovascular
Research Institute, University of California, San Francisco,
California, 94143-0521
Received for publication, September 21, 2000, and in revised form, October 3, 2000
 |
ABSTRACT |
Aquaporin (AQP) water channel AQP3 has been
proposed to be the major glycerol and non-AQP1 water transporter in
erythrocytes. AQP1 and AQP3 are also expressed in the kidney where
their deletion in mice produces distinct forms of nephrogenic diabetes
insipidus. Here AQP1/AQP3 double knockout mice were generated and
analyzed to investigate the functional role of AQP3 in erythrocytes and kidneys. 53 double knockout mice were born out of 756 pups from breeding double heterozygous mice. The double knockout mice had reduced
survival and impaired growth compared with the single knockout mice.
Erythrocyte water permeability was 7-fold reduced by AQP1 deletion but
not further reduced in AQP1/AQP3 null mice. AQP3 deletion did not
affect erythrocyte glycerol permeability or its inhibition by
phloretin. Daily urine output in AQP1/AQP3 double knockout mice (15 ml)
was 9-fold greater than in wild-type mice, and urine osmolality (194 mosM) was 8.4-fold reduced. The mice remained
polyuric after DDAVP administration or water deprivation. The
renal medulla in most AQP1/AQP3 null mice by age 4 weeks was atrophic
and fluid-filled due to the severe polyuria and hydronephrosis. Our
data provide direct evidence that AQP3 is not functionally important in
erythrocyte water or glycerol permeability. The renal function studies
indicate independent roles of AQP1 and AQP3 in countercurrent exchange
and collecting duct osmotic equilibration, respectively.
 |
INTRODUCTION |
The route for water movement across the erythrocyte plasma
membrane has been a subject of longstanding interest. Erythrocyte osmotic water permeability is inhibited by ~90% by mercurial
sulfhydryl compounds and has biophysical properties of a pore pathway
including a low Arrhenius activation energy and a high ratio of osmotic to diffusional water permeability (1). The water-selective transporter
AQP11 is the major
erythrocyte water transporter as proven by the reduced water
permeability in erythrocytes from Colton
/
humans lacking AQP1 (2)
and transgenic AQP1 null mice (3). Recently, immunocytochemical evidence has suggested that the "aquaglyceroporin" AQP3 provides the major non-AQP1 pathway for water transport across the erythrocyte plasma membrane as well as the transport pathway for glycerol (4).
Erythrocyte glycerol permeability is substantially greater than that
across lipid bilayers and is inhibited by phloretin (5); however, the
molecular identity of the putative glycerol transporter has not been
established. The principal goal of this study was to determine the
functional role of AQP3 in erythrocyte water and glycerol permeability.
Transport measurements were done on erythrocytes lacking AQP1 and AQP3
individually and AQP1/AQP3 together. We reasoned that the very low
water permeability of AQP1-deficient erythrocytes would permit the
detection of even small amounts of functional AQP3 as a further
decrease in permeability in AQP1/AQP3-deficient erythrocytes.
A secondary goal of this study was to investigate the roles of AQP1 and
AQP3 in the urinary-concentrating mechanism. AQP1 and AQP3 are
expressed in the kidney: AQP1 in proximal tubule, thin descending limb
of Henle, and medullary vasa recta (6, 7) and AQP3 at the basolateral
membrane of collecting duct principal cells (8, 9). Wild-type mice have
base-line urine osmolalities of 1000-1500 mosM that
increase to >3000 mosM after water deprivation. Mice
lacking AQP1 are polyuric and have urine osmolalities of 500-700
mosM that do not increase after water deprivation or
DDAVP administration (3). In vivo micropuncture revealed defective proximal tubule fluid absorption in AQP1 null mice
(10), and isolated tubule microperfusion showed remarkably reduced
osmotic water permeability in thin descending limb of Henle (11) and
outer medullary descending vasa recta (12). Mice lacking AQP3 also
manifest nephrogenic diabetes insipidus but with a very different
pattern (13). AQP3 null mice are remarkably polyuric with base-line
urine osmolalities of <280 mosM but are able to
concentrate their urine to 1000-1400 mosM after water deprivation or DDAVP administration.
In this study, mice lacking AQP1 and AQP3 were generated and
characterized. A comparison of water and glycerol permeabilities of
erythrocytes from the single and double knockout mice permitted a
direct assay of the functional role of AQP3. A comparison of urinary-concentrating ability in the single and double knockout mice
tested whether the different patterns of nephrogenic diabetes insipidus
result from distinct defects in countercurrent exchange and collecting
duct function.
 |
EXPERIMENTAL PROCEDURES |
Generation of AQP1/AQP3 Double Knockout Mice--
Because the
AQP1 and AQP3 genes are localized on different chromosomes in the mouse
genome, AQP1/AQP3 double knockout mice were generated by intercross of
the single knockouts. The breeding of F2 generation double heterozygous
mice yielded 53 AQP1/AQP3 knockout mice out of 756 pups.
Immunofluorescence--
Red blood cells and bone marrow
aspirates were smeared onto glass slides. Samples were fixed in
acetone/methanol (1:1) and incubated for 30 min with PBS containing 1%
bovine serum albumin and then incubated with AQP1 or AQP3
antiserum (1:1000) for 1 h at 23 °C in PBS containing 1%
bovine serum albumin. Slides were rinsed with 2.7% NaCl and then with
PBS, and they were incubated with a secondary Cy3-conjugated sheep
anti-rabbit F(ab)2 fragment (1:200) for visualization by
fluorescence microscopy.
Renal Function Studies--
Mice weighing 30-32 g were kept in
the mouse metabolic cages (Harvard Apparatus) for 24 h for
measurements of daily fluid consumption and urine output. For analysis
of urine osmolalities, urine samples were collected by placing mice on
a wire mesh platform in a clean glass beaker until spontaneous voiding
was observed. Urine osmolalities were measured by freezing point
depression osmometry (Micro-osmometer, Precision Systems, Inc.).
Water and Glycerol Permeability Measurements--
Fresh
erythrocytes obtained by tail bleeding (100-200 µl/bleed) were
washed three times in PBS to remove serum and the cellular buffy coat.
Stopped-flow measurements were carried out on a Hi-Tech Sf-51
instrument (Wiltshire, United Kingdom). For measurement of osmotic
water permeability, suspensions of erythrocytes (~0.5% hematocrit)
in PBS were subjected to a 100 mM inwardly directed gradient of sucrose. The kinetics of decreasing cell volume was measured from the time course of 90o scattered light
intensity at 530 nm wavelength. Osmotic water permeability coefficients
(Pf) were computed from the light-scattering time
course as described previously (14). For measurement of glycerol
permeability, the erythrocyte suspension was subjected to a 100 mM inwardly directed gradient of glycerol. In some
experiments, 0.3 mM HgCl2 or 0.5 mM
phloretin was added to the erythrocyte suspension before stopped-flow experiments.
Renal Morphology--
Mice were anesthetized by intraperitoneal
pentobarbital (30 mg/g body weight). Kidneys were fixed in
situ by perfusion with 4% paraformaldehyde in PBS. Fixed tissues
were processed by routine histological methods, and 6-µm paraffin
sections were stained with hematoxylin.
 |
RESULTS |
AQP1/AQP3 double knockout mice were generated by intercross of
AQP1 and AQP3 null mice. The mice were grossly phenotypically normal
when given free access to food and water except for obvious polyuria.
Over the first 10 weeks of life, the double knockout mice were 20-25%
smaller by body weight than wild-type littermates. At 6 weeks, the mean
body weights were 27.8 ± 2.4 g (wild-type) and 21.7 ± 3.2 g (AQP1/AQP3 knockout). The AQP1 null mice were 15-20%
smaller than wild-type mice, whereas the AQP3 null mice were not
impaired in their growth. The survival of AQP1/AQP3 double knockout
mice was also impaired compared with the single knockout mice. Although
>90% of living AQP1 and AQP3 null mice that were genotyped at 5 days
remained alive at 8 weeks, only 50% of the double knockout mice were
alive at 8 weeks.
Osmotic water permeability was measured in erythrocytes from wild-type
mice and mice lacking AQP1 and AQP3 individually and AQP1/AQP3
together. Fig. 1A shows the
time course of osmotic cell shrinking in response to a 100 mM inwardly directed osmotic gradient of sucrose. The data
are plotted using three contiguous time scales to show the full time
course of decreasing cell volume. Erythrocyte water permeability was
remarkably reduced by AQP1 deletion but not further reduced by AQP3
deletion. Fig. 1B shows the inhibition of water transport by
the mercurial HgCl2. Water transport was strongly inhibited
in erythrocytes from wild-type and AQP3 null mice and was inhibited to
a lesser extent in erythrocytes from AQP1 null mice and AQP1/AQP3
double knockout mice.

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Fig. 1.
Erythrocyte water permeability. Water
permeability was measured from the time course of erythrocyte volume as
determined by light scattering in response to a 100 mM
inwardly directed sucrose gradient. A, measurements in
erythrocytes from mice of indicated genotypes done at 10 °C.
B, measurements done in the presence of 0.3 mM
HgCl2. See explanation under "Results."
|
|
Fig. 2 summarizes osmotic water
permeability coefficients (Pf) determined in four
mice of each genotype. AQP3 deletion did not reduce
Pf in wild-type or AQP1 null mice nor did it affect
the inhibitory potency of HgCl2. Temperature dependence measurements were performed to determine the Arrhenius activation energy for erythrocyte water transport. Computed activation energies (10-37 °C) were <4 kcal/mol for wild-type and AQP3 null mice and >8 kcal/mol for AQP1 null mice and the double knockout mice.

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Fig. 2.
Summary of erythrocyte water permeability
properties. Osmotic water permeability coefficients
(Pf) for erythrocytes from mice of indicated
genotypes measured in the absence and presence of 0.3 mM
HgCl2 (four mice of each genotype, mean ± S.E.).
|
|
Erythrocyte glycerol permeability was measured from the time course of
cell swelling in response to a 100 mM inwardly directed gradient of glycerol. As shown in Fig.
3A, the glycerol gradient produced an initial rapid decrease in cell volume due to osmotically induced water efflux followed by slower cell swelling that was due to
glycerol and secondary water influx. At 20 °C, glycerol equilibrated
across erythrocytes from wild-type mice with a half-time of ~20 s,
giving a permeability coefficient (PGly) of
2.63 × 10
6 cm/s (top curve).
Glycerol permeability was inhibited by 64% by 0.5 mM
phloretin (second curve) and was strongly
temperature-sensitive (bottom curves), increasing 2.8-fold
from 10 to 30 °C that was consistent with a facilitated transport
pathway.

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Fig. 3.
Erythrocyte glycerol permeability.
Glycerol permeability was measured from the time course of erythrocyte
volume as determined by light scattering in response to a 100 mM inwardly directed glycerol gradient. A,
permeability measured in erythrocytes from wild-type mice in the
absence and presence of 0.5 mM phloretin at indicated
temperatures. B, glycerol permeability in erythrocytes from
AQP3 null mice in the absence and presence of phloretin. C,
summary of glycerol permeability coefficients from four mice (mean ± S.E.).
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Fig. 3B shows glycerol permeability in erythrocytes from
AQP3 null mice in the absence and presence of phloretin. Results were
similar to those in erythrocytes from wild-type mice. Data from a
series of mice showed that AQP3 deletion did not reduce erythrocyte
glycerol permeability or its inhibition by phloretin (Fig.
3C). Together the permeability measurements indicate that AQP3 does not contribute measurably to erythrocyte water or glycerol permeability.
Immunocytochemistry was done to look for AQP3 protein in erythrocytes.
Fig. 4A shows little AQP3
antibody labeling of permeabilized erythrocyte smears from humans
(left) and wild-type mice (middle). Similar low
levels of labeling were detected in erythrocytes from AQP3 null mice
(right). In contrast, AQP3 was readily detected in the
kidney-collecting duct in wild-type mice (Fig. 4B,
left) but not in AQP3 null mice (right).

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Fig. 4.
Immunodetection of AQP3 in erythrocytes and
kidney. A, immunofluorescence localization of AQP3 in
human erythrocytes (left) and erythrocytes from wild-type
(middle) and AQP3 null mice (right).
B, immunofluorescence of AQP3 in kidney cortex from
wild-type (left) and AQP3 null (right)
mice.
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|
Urinary-concentrating function was compared in the wild-type, single
knockout, and double knockout mice. Fig.
5A shows daily fluid
consumption and urinary output in the mice. Polydipsia and polyuria
were greater in AQP3 than in AQP1 null mice and further increased in
the AQP1/AQP3 double knockout mice. The difference in fluid intake and
urinary output, primarily representing insensible respiratory losses,
was similar in all groups. Fig. 5B summarizes urine
osmolalities in mice given free access to food and water and in mice
deprived of food and water for 24 h. Base-line urine osmolality was high (>1500 mosM) in wild-type mice and
nearly doubled after water deprivation. Base-line urine osmolality was much lower in the AQP1 null mice and changed little after water deprivation. Urine osmolality was lower in AQP3 null mice but increased 2.4-fold after water deprivation. Interestingly, the deletion
of AQP1 and AQP3 together resulted in an even lower base-line urine
osmolality, which unlike that in AQP1 null mice increased 2.9-fold
after water deprivation (see "Discussion").

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Fig. 5.
Renal function in aquaporin null mice.
A, daily fluid consumption (open bar) and urine
output (black bar) in mice of indicated genotype (four mice
in each group, mean ± S.E.). B, urine osmolality in
mice of indicated genotype measured during free access to water
(open bar) and after a 24-h water deprivation (black
bar) (four mice in each group, mean ± S.E.).
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Most adult AQP1/AQP3 double knockout mice showed marked tumor-like
swelling of the flanks bilaterally (Fig.
6A, left), which was never seen in wild-type mice. The flank swelling was caused by
kidney enlargement (Fig. 6A, middle and
right). Examination of the morphology in kidneys from
wild-type mice showed well demarcated cortex and papilla (Fig.
6B, top panels). In contrast, kidneys from AQP3
null mice (Fig. 6B, bottom panels) and AQP1/AQP3
double knockout mice (not shown) showed medullary atrophy and cortical thinning. At 4 weeks of age, >50% of kidneys from AQP3 null mice and
>90% of kidneys from AQP1/AQP3 double knockout mice showed these
changes. Many adult mice showed hydronephrosis. The kidneys with severe
hydronephrosis were markedly enlarged and transparent enough to reveal
dilated renal blood vessels (Fig. 6A, right
panel). Similar changes in renal morphology have been seen in
polyuria causing increased intrarenal pressures (15). The medullary
atrophy appeared to be an age-dependent phenomenon that was
infrequently seen in mice under the age of 2 weeks but found in ~50%
of mice at age 4 weeks (Fig. 6B). The mice with flank
swelling and renal enlargement had serum azotemia (blood urea nitrogen
78 ± 27 mg/dl, normal <15 mg/dl) and generally did not survive
beyond 10-12 weeks.

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Fig. 6.
Renal morphology in aquaporin null mice.
A, AQP3 null mouse with hydronephrosis (left) and
hydronephrotic kidneys (middle and right).
B, age-dependent progression of medullary
atrophy in AQP3 null mice. Paraffin sections of kidneys from mice of
indicated genotypes at different ages.
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|
 |
DISCUSSION |
The results here provide direct evidence against a role for AQP3
in erythrocyte water and glycerol permeabilities. The low osmotic water
permeability in AQP1-deficient erythrocytes was not further reduced by
AQP3 deletion. Erythrocyte glycerol permeability was not affected by
AQP3 deletion nor was the inhibition of glycerol permeability affected
by phloretin. The conclusion of the prior study suggesting a role for
AQP3 in erythrocyte water and glycerol transport was based primarily on
indirect immunocytochemical evidence (4). Our AQP3 antibodies were
unable to detect AQP3 in human or mouse erythrocytes by immunostaining,
whereas AQP3 was readily detected in the kidney-collecting duct.
Although small amounts of erythrocyte AQP3 expression cannot be ruled
out given the limitations of available antibodies, our data provide
functional evidence against an important contribution of AQP3 to
erythrocyte water and glycerol permeability.
The molecular mechanisms of erythrocyte glycerol transport and
non-AQP-mediated water transport remain unknown. The high and phloretin-inhibitable glycerol permeability suggests the existence of
an as yet unidentified glycerol transport protein.
Interestingly, the residual water permeability after AQP1 deletion was
partially inhibited by mercurials, suggesting the expression of another water-transporting protein. Erythrocytes contain UT-B
(originally called UT3 in rat and mouse and UT11 in human) (for review
see Refs. 16 and 17), a urea-transporting protein that also transports water when expressed in Xenopus oocytes (18); however,
quantitative analysis suggests that UT-B does not contribute
significantly to water permeability in native erythrocytes (19).
Measurement of water permeability in the erythrocytes lacking UT-B
should be informative and when available, transport measurements in
erythrocytes lacking UT-B and AQP1 together. Alternately, the non-AQP1
erythrocyte water transport pathway might involve a different aquaporin
or non-aquaporin water transporter, such as a water-permeable glucose carrier (20) or Na+-coupled solute cotransporter (21). As
in erythrocytes, water permeability in vesicles derived from the renal
proximal tubule is inhibited by mercurials (3). However, in contrast to
the data presented here on erythrocytes, water permeability in proximal tubule vesicles from AQP1 null mice is not inhibited by mercurials and
probably involves a lipid pathway.
Functional analysis of double knockout mice lacking two aquaporins has
been useful in analyzing the role of aquaporins in organs that express
more than one aquaporin. A small contribution of airway water channel
AQP4 to airspace-capillary water permeability was demonstrated by
comparative measurements in lungs from AQP1 null mice, which already
have low water permeability, with lungs from AQP1/AQP4 double knockout
mice (22). Similarly, the role of high basolateral membrane water
permeability in the kidney-collecting duct was quantified in functional
studies on mice lacking AQP3 versus AQP3/AQP4 together (13).
AQP3 is expressed mainly in the cortical and outer medullary-collecting
duct, whereas AQP4 is expressed mainly in the inner
medullary-collecting duct. Measurements in double knockout mice
provided information about whether the partial urinary-concentrating
ability of AQP3 null mice in response to water deprivation results from
residual AQP4-mediated water permeability in the inner
medullary-collecting duct. The roles of AQP1 (microvascular water
channel) and AQP5 (alveolar epithelial water channel) in lung
physiology were investigated using AQP1/AQP5 null mice (23). Although
airspace-capillary osmotic water permeability was reduced by more than
30-fold by AQP1/AQP5 deletion, active near-isosmolar alveolar fluid
absorption was not affected, providing strong evidence against a role
of aquaporins in lung physiology (24). We note that the AQP1/AQP3
double knockout mice generated for the experiments described here have
a greater impairment of growth and general robustness than the
previously created AQP1/AQP4, AQP1/AQP5, or AQP3/AQP5 double knockout
mice. Although the reason(s) for the relatively poor growth and
survival of AQP1/AQP3 null mice cannot be established from the data
presented here, we speculate that defective gastrointestinal function
might be involved. AQP1 null mice manifest dietary fat misprocessing
(25), and AQP3 appears to be expressed strongly throughout the
gastrointestinal tract (26, 27) so that their double deletion might
further compromise intestinal nutrient absorption.
Urinary-concentrating ability in mice lacking AQP1 and AQP3 together
was impaired to a greater extent than that in mice lacking AQP1 or AQP3
individually. AQP1 deletion results in defective isosmolar fluid
absorption in proximal tubule as well as in defective countercurrent
exchange, which produces a decrease in osmolality of the medullary
interstitium. Although the relative importance of decreased proximal
tubular absorption and defective thin descending limb of Henle and vasa
recta function (for countercurrent exchange) was not determined
directly, the vasa recta seemed more important based on the inability
of DDAVP to increase urine osmolality (3) and the compensatory
decrease in glomerular filtration rate in AQP1 null mice (10). The
polyuria in AQP1 null mice and their inability to produce concentrated
urine probably results from a maximal medullary osmolality of 600-700
mosM. If AQP3 deletion affects renal cortical function
(collecting duct water permeability, for review see Ref. 13) and the
countercurrent system, it is predicted that urine osmolality in well
hydrated mice should be very low and increase slightly in response to
DDAVP administration or water deprivation. We found that
compared with the results in well hydrated AQP3 null mice, urine
osmolality was mildly reduced, and urine output was increased in the
AQP1/AQP3 double knockout mice. The combined effects of low medullary
interstitial osmolality and reduced collecting duct water permeability
would account for this observation. Interestingly, urine osmolality in
water-deprived AQP1/AQP3 null mice increased substantially, albeit to a
level just lower than that in water-deprived AQP1 null mice. The
submaximal increase in transepithelial water permeability in the
AQP3-deficient cortical collecting duct in water-deprived AQP1/AQP3
double knockout mice permitted osmotic extraction of water in the
collecting duct lumen to produce a urine with osmolality >500 mosmol.
Together these results indicate distinct renal defects involving
medullary countercurrent exchange (AQP1) and cortical collecting duct
water permeability (AQP3). These data should be very useful in testing mathematical models of the urinary-concentrating mechanism.
 |
ACKNOWLEDGEMENT |
We thank Liman Qain for mouse breeding and
genotype analysis.
 |
FOOTNOTES |
*
This work was supported by National Institutes of Health
Grants DK35124, HL59198, HL60288 and DK43840 and Research Development Grant R613 from the National Cystic Fibrosis Foundation.The costs of publication of this
article were defrayed in part by the
payment of page charges. The article
must therefore be hereby marked
"advertisement" in
accordance with 18 U.S.C. Section
1734 solely to indicate this fact.
To whom correspondence should be addressed: 1246 Health Sciences
East Tower, Cardiovascular Research Inst., University of California,
San Francisco, CA 94143
0521. Tel.: 415-476-8530; Fax: 415-665-3847;
E-mail: verkman@itsa.ucsf.edu.
Published, JBC Papers in Press, October 16, 2000, DOI 10.1074/jbc.M008664200
 |
ABBREVIATIONS |
The abbreviations used are:
AQP, aquaporin;
PBS, phosphate-buffered saline.
 |
REFERENCES |
1.
|
Macey, R. I.
(1984)
Am. J. Physiol.
246,
C195-C203[Abstract]
|
2.
|
Macey, R. I.,
Mori, S.,
Smith, B. L.,
Preston, G. M.,
Mohandas, N.,
Collins, M.,
van Zili, P. C. M.,
Zeidel, M. L.,
and Agre, P.
(1996)
J. Biol. Chem.
271,
1309-1313[Abstract/Free Full Text]
|
3.
|
Ma, T.,
Yang, B.,
Gillespie, A.,
Carlson, E. J.,
Epstein, C. J.,
and Verkman, A. S.
(1998)
J. Biol. Chem.
273,
4296-4299[Abstract/Free Full Text]
|
4.
|
Roudier, N.,
Verbavatz, J.-M.,
Maurel, C.,
Ripoche, P.,
and Tacnet, F.
(1998)
J. Biol. Chem.
273,
8407-8412[Abstract/Free Full Text]
|
5.
|
Macey, R. I.,
and Farmer, R. E.
(1970)
Biochim. Biophys. Acta
211,
104-106[Medline]
[Order article via Infotrieve]
|
6.
|
Sabolic, I.,
Valenti, G.,
Verbavatz, J. M.,
Van Hoek, A. N.,
Verkman, A. S.,
Ausiello, D. A.,
and Brown, D.
(1992)
Am. J. Physiol.
263,
C1225-C1233[Abstract/Free Full Text]
|
7.
|
Nielsen, S.,
Smith, B. L.,
Christensen, E. I.,
Knepper, M. A.,
and Agre, P.
(1993)
J. Cell Biol.
120,
371-383[Abstract]
|
8.
|
Frigeri, A.,
Gropper, M.,
Turck, C. W.,
and Verkman, A. S.
(1995)
Proc. Natl. Acad. Sci. U. S. A.
92,
4328-4331[Abstract]
|
9.
|
Ecelbarger, C. A.,
Terris, J.,
Frindt, G.,
Echevarria, M.,
Marples, D.,
Nielsen, S.,
and Knepper, M. A.
(1995)
Am. J. Physiol.
269,
F663-F672[Abstract/Free Full Text]
|
10.
|
Schnermann, J.,
Chou, C. L.,
Ma, T.,
Traynor, T.,
Knepper, M. A.,
and Verkman, A. S.
(1998)
Proc. Natl. Acad. Sci. U. S. A.
95,
9660-9664[Abstract/Free Full Text]
|
11.
|
Chou, C. L.,
Knepper, M. A.,
van Hoek, A. N.,
Brown, D.,
Yang, B.,
Ma, T.,
and Verkman, A. S.
(1999)
J. Clin. Invest.
103,
491-496[Abstract/Free Full Text]
|
12.
|
Pallone, T. L.,
Edwards, A.,
Ma, T.,
Silldorff, E.,
and Verkman, A. S.
(2000)
J. Clin. Invest.
105,
2686-2692
|
13.
|
Ma, T.,
Song, Y.,
Yang, B.,
Gillespie, A.,
Carlson, E. J.,
Epstein, C. J.,
and Verkman, A. S.
(2000)
Proc. Natl. Acad. Sci. U. S. A.
97,
4386-4391[Abstract/Free Full Text]
|
14.
|
van Hoek, A. N.,
and Verkman, A. S.
(1992)
J. Biol. Chem.
267,
18267-18269[Abstract/Free Full Text]
|
15.
|
Takahashi, N.,
Chernavvsky, D. R.,
Gomez, R. A.,
Igarashi, P.,
Gitelman, H. J.,
and Smithies, O.
(2000)
Proc. Natl. Acad. Sci. U. S. A.
97,
5434-5439[Abstract/Free Full Text]
|
16.
|
Trinh-Trang-Tan, M. M.,
and Bankir, L.
(1998)
Exp. Nephrol.
6,
471-479[CrossRef][Medline]
[Order article via Infotrieve]
|
17.
|
Sands, J. M.
(1999)
J. Am. Soc. Nephrol.
10,
635-646[Abstract/Free Full Text]
|
18.
|
Yang, B.,
and Verkman, A. S.
(1998)
J. Biol. Chem.
273,
9369-9372[Abstract/Free Full Text]
|
19.
|
Sidoux-Walter, F.,
Lucien, N.,
Olives, B.,
Gobin, R.,
Rousselet, G.,
Kamsteeg, E. J.,
Ripoche, P.,
Deen, P. M.,
Cartron, J. P.,
and Bailly, P.
(1999)
J. Biol. Chem.
274,
30228-30235[Abstract/Free Full Text]
|
20.
|
Fischbarg, J.,
Kuang, K. Y.,
Hirsch, J.,
Lecuona, S.,
Rogozinski, L.,
Silverstein, S. C.,
and Loike, J.
(1989)
Proc. Natl. Acad. Sci. U. S. A.
86,
8397-8401[Abstract]
|
21.
|
Meinild, A. K.,
Loo, D. D.,
Pajor, A. M.,
Zeuthen, T.,
and Wright, E. M.
(2000)
Am. J. Physiol.
278,
F777-F783[Abstract/Free Full Text]
|
22.
|
Song, Y.,
Ma, T.,
Matthay, M. A.,
and Verkman, A. S.
(2000)
J. Gen. Physiol.
115,
17-27[Abstract/Free Full Text]
|
23.
|
Ma, T.,
Fukuda, N.,
Song, Y.,
Matthay, M. A.,
and Verkman, A. S.
(2000)
J. Clin. Invest.
105,
93-100[Abstract/Free Full Text]
|
24.
|
Verkman, A. S.,
Matthay, M. A.,
and Song, Y.
(2000)
Am. J. Physiol.
278,
L867-L879
|
25.
|
Ma, T.,
Jayaraman, S.,
Wang, K. S.,
Song, Y.,
Yang, B.,
Li, J.,
Bastidas, J. A.,
and Verkman, A. S.
(2001)
Am. J. Physiol.
280,
C126-C134[Abstract/Free Full Text]
|
26.
|
Silberstein, C.,
Kierbel, A.,
Amodeo, G.,
Zotta, E.,
Bigi, F.,
Berkowski, D.,
and Ibarra, C.
(1999)
Braz. J. Med. Biol. Res.
32,
1303-1131[Medline]
[Order article via Infotrieve]
|
27.
|
Ramirez-Lorca, R.,
Vizuete, M. L.,
Venero, J. L.,
Revuelta, M.,
Cano, J.,
Ilundain, A. A.,
and Echevarria, M.
(1999)
Pfluegers Arch. Eur. J. Physiol.
438,
94-100[CrossRef][Medline]
[Order article via Infotrieve]
|
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