In:
American Journal of Physiology-Gastrointestinal and Liver Physiology, American Physiological Society, Vol. 285, No. 6 ( 2003-12), p. G1242-G1248
Kurzfassung:
Previous studies have shown that gastric glands express at least sodium-hydrogen exchanger (NHE) isoforms 1-4. Our aim was to study NHE-3 localization in rat parietal cells and to investigate the functional activity of an apical membrane NHE-3 isoform in parietal cells of rats. Western blot analysis and immunohistochemistry showed expression of NHE-3 in rat stomach colocalizing the protein in parietal cells together with the β-subunit of the H + -K + -ATPase. Functional studies in luminally perfused gastric glands demonstrated the presence of an apical NHE isoform sensitive to low concentrations of 5-ethylisopropyl amiloride (EIPA). Intracellular pH measurements in parietal cells conducted in omeprazole-pretreated superfused gastric glands showed an Na + -dependent proton extrusion pathway that was inhibited both by low concentrations of EIPA and by the NHE-3 specific inhibitor S3226. This pathway for proton extrusion had a higher activity in resting glands and was inhibited on stimulation of histamine-induced H + -K + -ATPase proton extrusion. We conclude that the NHE-3 isoform located on the apical membrane of parietal cells offers an additional pathway for proton secretion under resting conditions. Furthermore, the gastric NHE-3 appears to work under resting conditions and inactivates during periods of H + -K + -ATPase activity.
Materialart:
Online-Ressource
ISSN:
0193-1857
,
1522-1547
DOI:
10.1152/ajpgi.00165.2003
Sprache:
Englisch
Verlag:
American Physiological Society
Publikationsdatum:
2003
ZDB Id:
1477329-6
SSG:
12
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