Characterization of Na+/H+ Exchanger Isoform (NHE1, NHE2 and NHE3) Expression in Prairie Dog Gallbladder

Characterization of Na+/H+ Exchanger Isoform (NHE1, NHE2 and NHE3) Expression in Prairie Dog... Gallbladder Na+ absorption is linked to gallstone formation in prairie dogs. Na+/H+ exchange (NHE) is one of the major Na+ absorptive pathways in gallbladder. In this study, we measured gallbladder Na+/H+ exchange and characterized the NHE isoforms expressed in prairie dogs. Na+/H+ exchange activity was assessed by measuring amiloride-inhibitable transepithelial Na+ flux and apical 22Na+ uptake using dimethylamiloride (DMA). HOE-694 was used to determine NHE2 and NHE3 contributions. Basal J Na ms was higher than J Na sm with J Na net absorption. Mucosal DMA inhibited transepithelial Na+ flux in a dose-dependent fashion, causing J Na ms equal to J Na sm and blocking J Na net absorption at 100 μm. Basal 22Na+ uptake rate was 10.9 ± 1.0 μmol · cm−2· hr−1 which was inhibited by ∼43% by mucosal DMA and ∼30% by mucosal HOE-694 at 100 μm. RT-PCR and Northern blot analysis demonstrated expression of mRNAs encoding NHE1, NHE2 and NHE3 in the gallbladder. Expression of NHE1, NHE2 and NHE3 polypeptides was confirmed using isoform-specific anti-NHE antibodies. These data suggest that Na+/H+ exchange accounts for a substantial fraction of gallbladder apical Na+ entry and most of net Na+ absorption in prairie dogs. The NHE2 and NHE3 isoforms, but not NHE1, are involved in gallbladder apical Na+ uptake and transepithelial Na+ absorption. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Characterization of Na+/H+ Exchanger Isoform (NHE1, NHE2 and NHE3) Expression in Prairie Dog Gallbladder

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Publisher
Springer-Verlag
Copyright
Copyright © Inc. by 2001 Springer-Verlag New York
Subject
Life Sciences; Biochemistry, general; Human Physiology
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-001-0038-9
Publisher site
See Article on Publisher Site

Abstract

Gallbladder Na+ absorption is linked to gallstone formation in prairie dogs. Na+/H+ exchange (NHE) is one of the major Na+ absorptive pathways in gallbladder. In this study, we measured gallbladder Na+/H+ exchange and characterized the NHE isoforms expressed in prairie dogs. Na+/H+ exchange activity was assessed by measuring amiloride-inhibitable transepithelial Na+ flux and apical 22Na+ uptake using dimethylamiloride (DMA). HOE-694 was used to determine NHE2 and NHE3 contributions. Basal J Na ms was higher than J Na sm with J Na net absorption. Mucosal DMA inhibited transepithelial Na+ flux in a dose-dependent fashion, causing J Na ms equal to J Na sm and blocking J Na net absorption at 100 μm. Basal 22Na+ uptake rate was 10.9 ± 1.0 μmol · cm−2· hr−1 which was inhibited by ∼43% by mucosal DMA and ∼30% by mucosal HOE-694 at 100 μm. RT-PCR and Northern blot analysis demonstrated expression of mRNAs encoding NHE1, NHE2 and NHE3 in the gallbladder. Expression of NHE1, NHE2 and NHE3 polypeptides was confirmed using isoform-specific anti-NHE antibodies. These data suggest that Na+/H+ exchange accounts for a substantial fraction of gallbladder apical Na+ entry and most of net Na+ absorption in prairie dogs. The NHE2 and NHE3 isoforms, but not NHE1, are involved in gallbladder apical Na+ uptake and transepithelial Na+ absorption.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Jul 15, 2001

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