From The Department of Physiology, University of
Texas Southwestern Medical Center, Dallas, Texas 75235, ¶ The
Department of Medicine, Division of Nephrology, ULCA, Los Angeles,
California,
Department of Pharmacology and Brain Korea 21 Project for Medical Sciences, Yonsei University College of Medicine,
Seoul 120-752, Korea
Received for publication, September 19, 2000, and in revised form, December 4, 2000
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ABSTRACT |
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In the present work, we
characterized H+ and HCO HCO Commonly, fluid and electrolyte secretion by epithelia occurs in two
steps. Acinar cells secrete a plasma-like fluid containing about 140 mM NaCl and 25 mM
HCO At the resting state HCO H+/HCO In the present work, we first analyzed
H+/HCO Materials and Solutions--
2'7'-bis
(carboxyethyl)-5-carboxyfluorescein)-AM (BCECF-AM) and
H2DIDS were from Molecular Probes, and collagenase CLS4 was from Worthington, Freehold, NJ. EIPA was from Research Biochemicals International, and DIDS was from Sigma. HOE 694 was a generous gift from Dr. Hans Lang, Avertis, Frankfurt am Main, Germany. Two
affinity-purified polyclonal antibodies were raised against synthetic
peptides derived from the N terminus of pNBC1: pNBC1a (amino acids
1-19) and pNBC1b (amino acids 51- 69, coupled to an N-terminal
cysteine). The affinity-purified polyclonal antibody to kNBC1 was
raised against a synthetic peptide corresponding to amino acids 11-24,
coupled to an N-terminal cysteine. The polyclonal antibody against NBC3
was raised against a synthetic peptide corresponding to amino acids
1197-1214 of the C terminus of NCB3 (19). This sequence is almost
identical to the C-terminal sequence of the known rodent NBC3 splice
variants (20). The standard perfusion solution (solution A) contained
140 mM NaCl, 5 mM KCl, 1 mM
MgCl2, 1 mM CaCl2, 10 mM HEPES (pH 7.4 with NaOH), and 10 mM glucose. Na+-free solutions were prepared by replacing
Na+ with
N-methyl-D-glucamine+.
HCO Animals and Preparation of Cells--
Mice with targeted
disruption of the NHE2 and NHE3 genes were
generated as described previously (21, 22). Heterozygote NHE2+/
The procedures for preparation of isolated interlobular ducts and acini
and for preparation and perfusion of the main SMG duct were similar to
those described before (11). In brief, for preparation of a mixture of
acini and interlobular ducts, the mouse SMGs were removed into solution
A supplemented with 10 mM sodium pyruvate, 0.02% trypsin
inhibitor, and 0.1% bovine serum albumin (PSA), minced, and digested
in the same solution that contained 0.5 mg/ml collagenase CLS4. The
digested tissue was washed three times with PSA, and the cells were
used for measurement of pHi. For perfusion of the main duct,
the mice were anesthetized, and the SMGs were exposed and cleared of
connective tissue around the ducts. The ducts were cut and transferred
to a perfusion chamber and prepared for luminal and bath perfusion. For
pHi measurement, ducts were loaded with BCECF by including the
BCECF-AM in the luminal perfusate.
Measurement of pHi--
Isolated ducts and acini were
incubated with 2 µM BCECF-AM for 10 min at room
temperature, washed once with PSA, and kept on ice until plating on
coverslips in the perfusion chamber. Fluorescence of isolated cells or
the perfused ducts was measured by photon counting using a Photon
Technology International system. BCECF fluorescence was recorded
at excitation wavelengths of 440 and 490 nm and an emission wavelength
above 530 nm. The 490/440 fluorescence ratios were calibrated using the
high potassium nigericin procedure described before (11, 14).
RT-PCR Analysis of NBC3 Splice Variants--
For preparation of
mRNA, digested cells were placed in a Petri dish, and about 30-50
acinar clusters of 3-5 cells or small duct fragments were collected by
glass micropipettes pre-soaked in solution A containing 25 mg/ml bovine
serum albumin. This procedure was used to avoid possible contamination
of the preparations with nerve terminals and blood vessels and
contamination of acinar and duct cells with each other. The cells were
ejected into an mRNA extraction solution to prepare mRNA and
then cDNA, as detailed before (11). The PCR primers used to
detect the transcripts shown in Fig. 5 are as follows: Immunocytochemistry--
Isolated cells and tissue sections were
placed on a polylysine-coated glass coverslips and allowed to attach
for at least 30 min at room temperature before fixation and
permeabilization with cold methanol. The staining procedure and various
solutions used are listed in Refs. 11 and 13. All primary antibodies used in the present work were affinity-purified. Each of the primary antibodies was incubated with the peptide used to raise the antibodies, and the peptide-blocked antibodies were used as controls. The antibodies were used at a 1:250-1:500 dilution and detected by a
fluorescein-tagged secondary donkey anti-rabbit antibodies. Images were
collected by a Bio-Rad MRC 1024 confocal microscope.
NHEs in the Mouse SMG Duct--
Previous work reported an EIPA-
and HOE-sensitive, Na+-dependent H+
efflux (or OH
Fig. 1 indicates that the mouse SMG duct expresses HOE-sensitive,
Na+-dependent H+/OH
The results in Fig. 2 are different from those obtained in the kidney
proximal tubule (23) and the pancreatic duct (13), in which deletion of
NHE3 reduced the rate of Na+-dependent
H+/OH
Semi-quantitative RT-PCR analysis and immunolocalization led us (11)
and others (12) to conclude expression of functional NHE1 in the BLM of
acinar and duct cells, NHE2 in the LM of SMG and NHE3 in the LM of the
parotid gland (11, 12) ducts. As indicated above, RT-PCR analysis with
mRNA prepared from SMG intraolublar duct fragments, collected
individually with micropipettes to ensure the origin of mRNA,
showed expression of NHE1, NHE2, and NHE3 in the mouse SMG duct,
confirming the immunolocalization of these proteins in the mouse SMG
(11). Measurement of H+/OH
Of particular significance is the similar HOE sensitivity of the
H+/OH NBC Isoforms in the Mouse SMG Acinar and Duct Cells--
In an
effort to identify the novel H+/OH
Next, we used two anti-pNBC1-specific and an anti-NBC3-specific
antibodies to localize the proteins by confocal immunofluorescence microscopy. Fig. 6 shows that both cell
types express pNBC1 in the BLM. The two anti-pNBC1 antibodies gave
similar patterns of staining of the basal and lateral membranes and no
staining of the LM, including in the duct. The anti-NBC3 antibodies
were raised against a C-terminal peptide (19) that is highly homologous in all NBC3 splice variants (20) and is, thus, likely to detect expression of all NBC3 isoforms. Panels G-J of Fig. 6 show
that the anti-NBC3 antibodies strongly stained the LM of the SMG ducts. Fig. 6J shows that the antibodies also stained the LM and
what appears as a web of canaliculi emanating from acinar cells and draining into the intercalated duct. Hence, both the SMG acinar and
duct cells express the electroneutral NBC3 in the LM.
In experiments parallel to those in Fig. 6, we used antibodies that
specifically recognized kNBC1. These antibodies showed strong staining
of the kidney proximal tubule but did not stain any of the cells of the
SMG (not shown). Hence, in agreement with the RT-PCR results in Fig. 5,
both SMG cell types express only pNBC1 in the BLM.
The lack of luminal Na+-dependent
H+/OH Na+-HCO
Because SMG cells express several NBC isoforms (Figs. 5 and 6), we
attempted to develop experimental protocols to isolate the activity of
the isoforms based on possible differences in the ability to transport
OH
An additional finding of note in Fig. 7, A and B,
is that in the absence of HCO
Using the same protocols with the SMG duct revealed the presence of
similar mechanisms with one major and important exception. The base
transport mechanism with the higher IC50 for EIPA appears to transport both OH Functional localization of
OH
The results in Figs. 1 and 9A indicate that a transporter
with HOE and EIPA sensitivity typical of NHE1 is functional in the BLM
of the SMG duct. This is consistent with immunolocalization of NHE1 in
the BLM of the mouse SMG ducts (11) and with a recent report of
impaired pHi regulation in parotid acinar cells of NHE1
The effects of HCO
Although none of the findings on its own is sufficient to identify with
certainty the transporters in the SMG acinar and duct cells that
mediate the Na+-dependent, DIDS-insensitive
HCO
A significant problem with this interpretation is that NBCn1B was found
to transport HCO
In summary, the present work provides new information on the mechanism
of
H+/OH
We identified a Na+-dependent,
EIPA-sensitive/DIDS-insensitive
H+/HCO
On the other hand, it appears paradoxical to find
Na+-dependent
HCO
At present, it is unknown how HCO/
, NHE3
/
, and NHE2
/
;NHE3
/
double knock-out mice. The bulk of recovery from an acid load across
the luminal membrane (LM) of the duct was mediated by a Na+-dependent HOE and
ethyl-isopropyl-amiloride (EIPA)-inhibitable and
4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS)-insensitive mechanism. HCO
and/or HCO
. By contrast, duct cell NBC3 transported both
OH
and HCO
INTRODUCTION
TOP
ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS AND DISCUSSION
REFERENCES
and secrete
HCO
absorption by these cells has been extensively
studied, few studies have examined the mechanism of
HCO
(and sometime the Na+, as is
the case in the lung (3) and the submandibular salivary gland (SMG)
(1)) and secretes as much as 140 mM
HCO
absorption and
HCO
-low HCO
absorption are tightly coupled (1-4), which is interpreted in most
models to mean that Cl
absorption and
HCO
/HCO
/HCO
/
and/or NHE3
/
mice.
/
,
NHE3
/
, and NHE2
/
;NHE3
/
double knock-out mice. We found
functional NHE1-like activity in the BLM, and although expressed in
duct cells, neither NHE2 nor NHE3 participates in
H+/HCO
and HCO
/HCO
EXPERIMENTAL PROCEDURES
TOP
ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS AND DISCUSSION
REFERENCES
with 25 mM NaHCO3 or choline-HCO3,
respectively, and reducing HEPES to 5 mM.
HCO
;NHE3+/
mice were mated to generate the homozygote double knock-out NHE2
/
;NHE3
/
mice. Animals were typed by tail DNA before use. Deletion of the proteins was verified by Western blot (23)
and immunocytochemistry (11, 12). Animals had free access to food and
water and were used at 1-2 months of age.
-actin sense,
TGTTACCAACTGGGACGACA, antisense, TCTCAGCTGTGGTGGTGAAG (392 bp); pNBC1
sense, ATGTGTGTGATGAAGAAGAAGTAGAAG, antisense, GACCGAAGGTTGGATTTCTTG
(622 bp); kNBC1 sense, CACTGAAAATGTGGAAGGGAAG, antisense,
GACCGAAGGTTGGATTTCTTG (531 bp); NBCn1B+D sense, CTGACCCTCACTTGCTTGAA, antisense, CTATGTCTTCCTCAGGCGGAT (342 bp); NBCn1C sense,
ATAGGGAAAGGCCTGTCAGCCTC, antisense, GAGAAGCCAAAATCCCTGG (389 bp);
NBCn1B sense, TCCGATGCCAGTTCTATATGG, antisense, CAGGGCTATATTTTAGGGTC
(473 bp); NBCn1C+D sense, AGAGCAGAAGAATGAGGAA, antisense,
TCATGGAAAGTGCCTTCCAC (2.54 kilobase pairs); NBCn1D sense,
CTGACCCTCACTTGCTTGAA, antisense, TCATGGAAAGTGCCTTCCAC (2.9 kilobase pairs). Except for NBCn1C+D and NBCn1D, the conditions for all
PCR reactions were a hot start of 3 min at 95 °C followed by 35 cycles of 1 min at 94 °C, 90 s at 58 °C, and 1 min at
72 °C. Reactions were terminated by a 5-min incubation at 72 °C
and cooling to 10 °C. For NBCn1C+D and NBCn1D, the 35 cycles were 1 min at 94 °C, 150 s at 60 °C, and 150 s at 72 °C.
All short amplified PCR products were isolated and sequenced to verify
their identity. Between 600-700 bases were sequenced from each end of NBCn1C+D and NBCn1D fragments and found to be 100% identical to the
corresponding sequences. The NBCn1C+D primers were used to ascertain
the lack of mRNA for these NBC3 splice variants in the duct.
RESULTS AND DISCUSSION
TOP
ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS AND DISCUSSION
REFERENCES
influx) mechanism in isolated rat SMG
acinar and duct cells (11, 24). Fig. 1
extends these findings to cells from the mouse SMG so that mice with
disrupted genes can be used to study the role of the transporters of
interest in cellular
H+/OH
/HCO
influx) in the BLM and LM of the perfused mouse SMG
duct. Similar to findings with the rat SMG (11), the BLM activity was
completely inhibited by 5 µM HOE. By contrast, 50 µM HOE were needed to inhibit the LM activity by about
86 ± 11% (n = 7).
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Fig. 1.
Localization of HOE-sensitive transporters in
the mouse SMG duct. Intralobular ducts (panel A) loaded
with BCECF were perfused with solution A containing 140 mM
NaCl. At the time indicted by the bars, the ducts were
perfused with a Na+-free solution and transiently exposed
to 20 mM NH4+ to reduce pHi
to about 6.6. Na+-dependent pHi
recovery was measured by perfusing the ducts with solution A. The
effect of HOE on the rate of recovery from pHi was measured by
including the indicated concentration of HOE in the perfusate. The
first derivative of the ascending portion of each trace was used to
calculate the effect of HOE, and the results of multiple experiments
are plotted in Fig. 4. In panel B, the main duct of the
mouse SMG was perfused with separate bath and luminal solutions.
Filled columns indicate perfusion with solution A containing
140 mM NaCl, and open columns indicate perfusion
with Na+-free solutions.
NH
transporters in both the BLM and the LM. RT-PCR analysis with mRNA
preparations from the mouse SMG acinar and duct cells, similar to that
we reported for the rat SMG cells (11) and the mouse pancreatic duct
(13), showed that the mouse SMG acinar cells express mRNA for NHE1,
and the mouse SMG duct expresses mRNA for NHE1, NHE2, and NHE3 but
not for NHE4 and NHE5 (not shown). Based on the sensitivity to HOE of
the known NHE isoforms (25), the results in Fig. 1B suggest
that the duct expresses functional NHE1 in the BLM and NHE2 in the LM.
However, further analysis of Na+-dependent
H+/OH
transport in ducts from NHE knockout
mice showed that this is not the case. Fig.
2 shows individual examples, and Fig. 4
summarizes the results of multiple experiments performed with SMG ducts
prepared from NHE2
/
and NHE3
/
mice. The
Na+-dependent H+/OH
fluxes and their sensitivity to HOE were the same in SMG ducts of WT,
NHE2
/
, and NHE3
/
mice.
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Fig. 2.
Na+-dependent
recovery from an acid load in ducts from the SMG of
NHE2 /
and
NHE3
/
mice. The
protocol of Fig. 1A was used to measure the effect of
different concentrations of HOE on
Na+-dependent recovery from an acid load in the
SMG intralobular ducts of NHE2
/
(A) or NHE3
/
mice
(B). Similar experiments were performed with at least five
ducts obtained from three mice of each genotype and are plotted in Fig.
4.
fluxes across the LM by about 50%. One
possibility is that deletion of NHE3 from the SMG resulted in a
compensatory increase in NHE2 activity. To address this possibility, we
obtained a double NHE2
/
;NHE3
/
knock-out mice and measured
H+/OH
fluxes in
SMG acinar and duct cells of these mice. Figs.
3A and 4 show that the HOE sensitivity of
Na+-dependent H+/OH
fluxes in SMG intralobular ducts of WT and NHE2
/
;NHE3
/
mice are
no different. Fig. 3B shows that in the absence of
HCO
/
; NHE3
/
mice. Finally, Fig. 3C shows that the properties of the BLM and the LM
H+/OH
fluxes in the main SMG duct of the
NHE2
/
;NHE3
/
mice are not different from those found for the SMG
ducts of WT mice (Fig. 1).
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Fig. 3.
Na+-dependent
recovery from an acid load in acini and ducts from the SMG of
NHE2 /
;NHE3
/
double knock-out mice. The protocol of Fig. 1A
was used to evaluate the HOE sensitivity of the
Na+-dependent recovery from an acid load of
intralobular ducts (A) or acini (B) prepared from
the SMG of NHE2
/
;NHE3
/
mice. Similar experiments were performed
with ducts obtained from four animals, and acini were obtained from
three animals. The protocol of Fig. 1B was used to measure
the effect of basolateral and luminal HOE on the
Na+-dependent pHi recovery of acidified
main SMG ducts (C). Similar results were obtained with four
ducts from four animals.
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Fig. 4.
HOE sensitivity of
Na+-dependent H+/OH
transport by the SMG intralobular duct of WT and mutant mice.
Results of experiments similar to those in Figs. 1-3 were summarized
and plotted to calculate the IC50 for HOE in acini from WT
mice and ducts from WT and mutant mice.
fluxes and their
inhibition by amiloride analogs such as EIPA (9, 10, 12) or HOE (Ref.
11 and the present work), further suggested expression of functional
NHE1 in the BLM and NHE2 and/or NHE3 in the LM of the ducts. Therefore,
it was quite surprising to find that deletion of NHE2, NHE3 or both
proteins had no measurable effect on the
Na+-dependent, HOE-inhibitable
H+/OH
fluxes in either the BM or LM of the
mouse SMG duct.
fluxes in the SMG ducts of all animals.
This makes it unlikely that the similar rates of
H+/OH
fluxes are due to compensatory increase
in the activity of any NHE transporter. In this case, we would have
seen a change in the apparent affinity for HOE. These findings indicate
that previous conclusions concerning the identity of the proteins
mediating H+/OH
flux in the LM of salivary
gland ducts are not correct (9-12). Rather, neither NHE2 nor NHE3
contribute to H+/OH
fluxes across the LM of
the SMG duct, and HOE probably inhibits the activity of a
H+/OH
transporter other than NHE2 and NHE3.
This protein is expressed in the SMG duct and has the same activity and
HOE sensitivity in ducts from WT and all knock-out animals. The role of
NHE2 and NHE3 in salivary gland function remains a mystery.
flux
activity in the LM of the SMG duct and better understand
H+/OH
transport by acinar cells, we decided
to characterize the
Na+-HCO
in
a DIDS-insensitive, EIPA-inhibitable manner (19), which is reminiscent
of the H+/OH
flux activity in the LM of the
proximal tubule (23), pancreatic duct (13), and SMG duct (Ref. 11 and
present work). Several NBC isoforms have been identified in recent
years and are classified based on their activity as the electrogenic
kNBC1 (26) and pNBC1 (16) and the electroneutral hNBC3 (19) and the rat
NBC3 splice variants NBCn1B, NBCn1C, and NBCn1D (20). Shown in Fig.
5 is an RT-PCR analysis of the known NBC
isoforms in SMG acinar and duct cells. The mouse SMG acinar and duct
cells express mRNA coding for pNBC1 but not for kNBC1. Each of
these cell types expresses selective isoforms of the rodent NBCn1. SMG
acinar, but not duct, cells express mRNA for NBCn1C and NBCn1D
(Fig. 5, A, C, and D). SMG duct, but
not acinar, cells express mRNA for NBCn1B (Fig. 5B).
Primers that detect both NBCn1B+D (fourth lane in each blot) detected the expected transcript in mRNA prepared from SMG duct and
acinar cells, verifying expression of NBCn1B in the duct. Primers that
detect both NBCn1C+D (Fig. 5C) detected the expected transcript in mRNA prepared from SMG acinar cells. These primers were used to verify lack of expression of NBCn1C and NBC1D in duct
cells.
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Fig. 5.
RT-PCR analysis of NBC splice variants in SMG
acinar and duct cells. The primers listed under methods were used
to amplify the indicated products from mRNA prepared from SMG acini
(A, C, and D) or intralobular ducts
(B-D). An mRNA isolated from brain was used to obtain a
positive control for kNBC1 (B). Similar results were
obtained with at least three separate mRNA preparations from
different animals. In panels C and D, three
separate mRNA preparations from SMG acinar (A1-A3) or
duct (D1-D3) cells were used for the RT-PCR
reactions. kb, kilobases; M, markers.
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Fig. 6.
Immunolocalization of pNBC1and NBC3 in
SMG cells. Frozen sections (A-H and L) or
isolated cell clusters (I-K) were fixed and stained with
two different antibodies that recognize pNBC1 (antibodies a
(A-C) and antibodies b (D-F)) and antibodies
that recognize all NBC3 isoforms (G-L). For controls, the
peptides used to raise anti-pNBC1a (C), anti-pNBC1b
(F), and anti-NBC3 (H and K) were
incubated with the respective antibodies before use. Similar staining
patterns were observed in at least four experiments with each of the
antibodies. Antibodies specific for kNBC1 showed strong staining of the
kidney proximal tubule but did not stain any of the cells of the SMG
(not shown). Note that in panels A-K, cells were from SMG
of WT mice, whereas in panel L, cells were from SMG of
NHE2 /
;NHE3
/
double knock-out mice.
transport phenotype in the ducts of
NHE2
/
; NHE3
/
mice may have been due to up-regulation of NBC3
expression. Two findings argue against such an explanation. First, the
HOE sensitivity of the luminal mechanisms was the same in ducts from WT
and all mutant mice (Fig. 4). Second, we evaluated the level of NBC3
protein expression in cells of mutant mice by immunofluorescence. Fig.
6L shows that the level of NBC3 protein is similar in duct
and acini of WT and NHE2
/
;NHE3
/
mice.
, are
inhibitable by DIDS, and show no sensitivity to amiloride or any
amiloride analog (27). When expressed in Xenopus oocytes, NBC3 transports OH
and
HCO
transport (19). HCO
transport by NBC3 are not sensitive to DIDS but
are inhibited by EIPA (19). NBCn1B expressed in Xenopus
oocytes mediated an electroneutral Na+-
HCO
and HCO
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Fig. 7.
EIPA-sensitive
HCO
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Fig. 8.
EIPA-insensitive, DIDS-sensitive
HCO
and
HCO
/HCO
/HCO
/HCO
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Fig. 9.
Localization of
HCO
/
mice (30). Fig. 9A indicates that
HCO
/HCO
/HCO
and
HCO
and
HCO
, and the
isoform expressed in duct cells transports both
HCO
.
and to be insensitive to EIPA (20). However, NBCn1B
may behave differently when expressed in the heterologous system of
oocytes than in native cells. Furthermore, it is possible that in
native cells the NBC3 splice variants do not function individually but rather assemble into complexes to yield the OH
and/or
HCO
/HCO
/
mice (22, 23). This can be mediated by a
splice variant of NBC3 since a Na+-dependent,
EIPA-inhibitable acid-base transporter was found in the proximal tubule
of NHE2
/
;NHE3
/
double knockout mice (23).
and
HCO
/HCO
![]() |
ACKNOWLEDGEMENTS |
---|
We are grateful to Drs. Gary Shull and
Patrick Schultheis (University of Cincinnati) for providing us with
mating pairs of NHE2+/ and NHE3+/
mice. Karen Miller provided
excellent administrative support.
![]() |
FOOTNOTES |
---|
* This work was supported in part by National Institutes of Health Grants DE12309 and DK38938 (to S. M.), Basic Research Program of the Korea Science and Engineering Foundation Grant 2000-2-21400-002-1 (to M. G. L.), National Institutes of Health Grant DK46976, and by the Iris and B. Gerald Cantor Foundation, the Max Factor Family Foundation, the Verna Harrah Foundation, the Richard and Hinda Rosenthal Foundation, and the Fredericka Taubitz Foundation (to I. K.)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.
§ These authors contributed equally to this work.
** To whom correspondence should be addressed: Dept. of Pharmacology, Yonsei University College of Medicine, 134 Sinchon-Dong, Seoul 120-752, Korea. Tel.: 82 2 361 5221; Fax: 82 2 313 1894; E-mail: mlee@yumc.yonsei.ac.kr.
Published, JBC Papers in Press, January 3, 2001, DOI 10.1074/jbc.M008548200
![]() |
ABBREVIATIONS |
---|
The abbreviations used are:
CF, cystic fibrosis;
CFTR, cystic fibrosis transmembrane conductance regulator;
NHE, Na+/H+ exchanger;
NBC, Na+-
HCO
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REFERENCES |
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1. | Cook, D. I., van Lennep, E. W., Roberts, M. L., and Young, J. A. (1994) in Physiology of the Gastrointestinal Tract (Johnson, L. R., ed), 3rd Ed. , pp. 1061-1117, Raven Press, Ltd., New York |
2. | Argent, B. E., and Case, R. M. (1994) in Physiology of the Gastrointestinal Tract (Johnson, L. R., ed), 3rd Ed. , pp. 1478-1498, Raven Press, Ltd., New York |
3. | Pilewski, J. M., and Frizzell, R. A. (1999) Physiol. Rev. 79, S215-S255[Medline] [Order article via Infotrieve] |
4. | Grubb, B. R., and Boucher, R. C. (1999) Physiol. Rev. 79, S193-S213[Medline] [Order article via Infotrieve] |
5. | Johansen, P. G., Anderson, C. M., and Hadorn, B. (1968) Lancet 1, 455-460[CrossRef] |
6. | Kopelman, H., Corey, M., Gaskin, K., Durie, P., Weizman, Z., and Forstner, G. (1988) Gastroenterology 95, 349-355[Medline] [Order article via Infotrieve] |
7. |
Lee, M. G.,
Wigley, W. C.,
Zeng, W.,
Noel, L. E.,
Marino, C. R.,
Thomas, P. J.,
and Muallem, S.
(1999)
J. Biol. Chem.
274,
3414-3421 |
8. |
Lee, M. G.,
Choi, J. Y.,
Luo, X.,
Strickland, E.,
Thomas, P. J.,
and Muallem, S.
(1988)
J. Biol. Chem.
274,
14670-14677 |
9. |
Paulais, M.,
Cragoe, E. J., Jr.,
and Turner, R. J.
(1994)
Am. J. Physiol.
266,
C1594-C1602 |
10. | Chaturapanich, G., Ishibashi, H., Dinudom, A., Young, J. A., and Cook, D. I. (1997) J. Physiol. 503, 583-598[Abstract] |
11. |
Lee, M. G.,
Schultheis, P. J.,
Yan, M.,
Shull, G. E.,
Bookstein, C.,
Chang, E.,
Tse, M.,
Donowitz, M.,
Park, K.,
and Muallem, S.
(1998)
J. Physiol.
513,
341-357 |
12. |
Park, K.,
Olschowka, J. A.,
Richardson, L. A.,
Bookstein, C.,
Chang, E. B.,
and Melvin, J. E.
(1999)
Am. J. Physiol.
276,
G470-G478 |
13. |
Lee, M. G.,
Ahn, W.,
Choi, J. Y.,
Luo, X.,
Seo, J. T.,
Schultheis, P. J.,
Shull, G. E.,
Kim, K. H.,
and Muallem, S.
(2000)
J. Clin. Invest.
105,
1651-1658 |
14. |
Muallem, S.,
and Loessberg, P. A.
(1990)
J. Biol. Chem.
265,
12806-12812 |
15. |
Muallem, S.,
and Loessberg, P. A.
(1990)
J. Biol. Chem.
265,
12813-12819 |
16. |
Abuladze, N.,
Lee, I.,
Newman, D.,
Hwang, J.,
Boorer, K.,
Pushkin, A.,
and Kurtz, I.
(1998)
J. Biol. Chem.
273,
17689-17695 |
17. | Marino, C. R., Jeanes, V., Boron, W. F., and Schmitt, B. M. (1999) Am. J. Physiol. 277, G487-G494[Medline] [Order article via Infotrieve] |
18. | Thevenod, F., Roussa, E., Schmitt, B. M., and Romero, M. F. (1999) Biochem. Biophys. Res. Commun 264, 291-298[CrossRef][Medline] [Order article via Infotrieve] |
19. |
Pushkin, A.,
Abuladze, N.,
Lee, I.,
Newman, D.,
Hwang, J.,
and Kurtz, I.
(1999)
J. Biol. Chem
274,
16569-16575 |
20. | Choi, I., Aalkjaer, C., Boulpaep, E. L., and Boron, W. F. (2000) Nature 405, 571-575[CrossRef][Medline] [Order article via Infotrieve] |
21. |
Schultheis, P. J.,
Clarke, L. L.,
Meneton, P.,
Harline, M.,
Boivin, G. P.,
Stemmermann, G.,
Duffy, J. J.,
Doetschman, T.,
Miller, M. L.,
and Shull, G. E.
(1998)
J. Clin. Invest.
101,
1243-1253 |
22. | Schultheis, P. J., Clarke, L. L., Meneton, P., Miller, M. L., Soleimani, M., Gawenis, L. R., Riddle, T. M., Duffy, J. J., Doetschman, T., Wang, T., Giebisch, G., Aronson, P. S., Lorenz, J. N., and Shull, G. E. (1998) Nat. Genet. 19, 282-285[CrossRef][Medline] [Order article via Infotrieve] |
23. |
Shah, M.,
Lee, M. G.,
Schulcheis, P. J.,
Shull, G. E.,
Muallem, S.,
and Baum, M.
(2000)
J. Clin. Invest.
105,
1141-1146 |
24. |
Zhao, H.,
Xu, X.,
Diaz, J.,
and Muallem, S.
(1995)
J. Biol. Chem.
270,
19599-19605 |
25. |
Noel, J.,
and Pouyssegur, J.
(1995)
Am. J. Physiol.
268,
C283-C296 |
26. | Romero, M. F., Hediger, M. A., Boulpaep, E. L., and Boron, W. F. (1997) Nature 387, 409-413[CrossRef][Medline] [Order article via Infotrieve] |
27. | Romero, M. F., and Boron, W. F. (1999) Annu. Rev. Physiol. 61, 699-723[CrossRef][Medline] [Order article via Infotrieve] |
28. | Bobik, A., Neylon, C. B., Little, P. J., Cragoe, E. J., Jr., and Weissberg, P. L. (1990) Clin. Exp. Pharmacol. Physiol. 17, 297-301[Medline] [Order article via Infotrieve] |
29. | Little, P. J., Neylon, C. B., Farrelly, C. A., Weissberg, P. L., Cragoe, E. J., Jr., and Bobik, A. (1995) Cardiovasc. Res. 29, 239-246[CrossRef][Medline] [Order article via Infotrieve] |
30. |
Evans, R. L.,
Bell, S. M.,
Schultheis, P. J.,
Shull, G. E.,
and Melvin, J. E.
(1999)
J. Biol. Chem.
274,
29025-29030 |
31. | Ishiguro, H., Steward, M. C., Lindsay, A. R. G., and Case, R. M. (1996) J. Physiol. (Lond.) 495, 169-178[Abstract] |
32. |
Ishiguro, H.,
Naruse, S.,
Steward, M. C.,
Kitagawa, M.,
Ko, S. H. B.,
Hayakawa, T.,
and Case, R. M.
(1998)
J. Physiol. (Lond.)
511,
407-422 |
33. | Zhao, H., Star, R. A., and Muallem, S. (1994) J. Gen. Physiol. 104, 57-85[Abstract] |
34. | Lerch, M. M., and Gorelick, F. S. (2000) Med. Clin. N. Am. 84, 549-563[Medline] [Order article via Infotrieve] |