In:
American Journal of Physiology-Renal Physiology, American Physiological Society, Vol. 282, No. 5 ( 2002-05-01), p. F835-F843
Kurzfassung:
In the proximal tubule, the apical Na + /H + exchanger identified as NHE3 mediates most NaCl and NaHCO 3 absorption. The purpose of this study was to analyze the long-term regulation of NHE3 during alkalosis induced by dietary NaHCO 3 loading and changes in NaCl intake. Sprague-Dawley rats exposed to a low-NaCl, high-NaCl, or NaHCO 3 diet for 6 days were studied. Renal cortical apical membrane vesicles (AMV) were prepared from treated and normal rats. Na + /H + exchange was assayed as the initial rate of 22 Na + uptake in the presence of an outward H + gradient. 22 Na + uptake measured in the presence of high-dose 5-( N-ethyl- N-isopropyl) amiloride was not different among models. Changes in NaCl intake did not affect NHE3 activity, whereas NaHCO 3 loading inhibited 22 Na + uptake by 30%. AMV NHE3 protein abundance assessed by Western blot analysis was unaffected during changes in NaCl intake. During NaHCO 3 loading, NHE3 protein abundance was decreased by 65%. We conclude that proximal NHE3 adapts to chronic metabolic acid-base disorders but not to changes in dietary NaCl intake.
Materialart:
Online-Ressource
ISSN:
1931-857X
,
1522-1466
DOI:
10.1152/ajprenal.00188.2001
Sprache:
Englisch
Verlag:
American Physiological Society
Publikationsdatum:
2002
ZDB Id:
1477287-5
