PMID: 8967348Apr 11, 1996Paper

Functional roles of apical membrane Na+/H+ exchange in rat medullary thick ascending limb

The American Journal of Physiology
David W Good, Bruns A Watts

Abstract

The medullary thick ascending limb (MTAL) of the rat actively absorbs both HCO3- and ammonium. The roles of apical membranes Na+/H+ exchange in these processes and in determining steady-state intracellular pH (pHi) were examined in MTAL perfused in vitro with solutions containing 146 mM Na+ and 25 mM HCO3- (pH 7.4). Addition of 1 mM amiloride or 50 microM ethylisopropylamiloride (EIPA) to the lumen decreased HCO3- absorption (JHCO3) from 10.6 +/- 0.5 to 2.3 +/- 0.3 pmol.min-1.mm-1 (P < 0.001) and pHi from 7.10 +/- 0.02 to 6.86 +/- 0.03 (P < 0.001). The combination of lumen Na+ replacement plus amiloride abolished JHCO3. Chronic metabolic acidosis (CMA) caused a 32% increase in JHCO3 that was inhibited by luminal amiloride. Addition of 4 mM NH4Cl to perfusate and bath markedly decreased pHi (from 7.10 to 6.70) but did not stimulate luminal H+ secretion as assessed by HCO3- absorption. With 4 mM NH4Cl in perfusate and bath, luminal addition of amiloride decreased pHi from 6.70 +/- 0.06 to 6.50 +/- 0.05 (P < 0.005) but had no effect on net ammonium absorption. These results demonstrate that 1) apical membrane Na+/H+ exchange mediates virtually all of HCO3- absorption and is an important determinant of steady-state pHi in the MTAL;...Continue Reading

Citations

Mar 27, 2003·American Journal of Physiology. Renal Physiology·Tae-Hwan KwonSøren Nielsen
Oct 28, 2005·American Journal of Physiology. Cell Physiology·David W GoodBruns A Watts
May 23, 2014·American Journal of Physiology. Renal Physiology·Aurélie EdwardsAnita T Layton
Oct 13, 2000·American Journal of Physiology. Cell Physiology·D W GoodB A Watts
Nov 13, 2001·American Journal of Physiology. Renal Physiology·T WangG Giebisch
May 23, 2015·American Journal of Physiology. Renal Physiology·Pauline I A de BruijnJens Leipziger
Mar 18, 2004·American Journal of Physiology. Renal Physiology·Bruns A Watts, David W Good
Aug 18, 2006·Current Opinion in Nephrology and Hypertension·Tong Wang
Mar 7, 2002·American Journal of Physiology. Renal Physiology·Soline BourgeoisPascal Houillier
May 10, 2006·American Journal of Physiology. Renal Physiology·Marcela HerreraJeffrey L Garvin
Sep 1, 2000·American Journal of Physiology. Renal Physiology·H AmlalM Soleimani
Dec 17, 2009·American Journal of Physiology. Renal Physiology·Aurélie Edwards
Nov 20, 2009·American Journal of Physiology. Renal Physiology·Alan M Weinstein, Thomas A Krahn
Sep 10, 2002·American Journal of Physiology. Renal Physiology·David W GoodBruns A Watts
Jan 3, 2001·American Journal of Physiology. Renal Physiology·A Attmane-ElakebM Bichara
Jun 8, 2006·American Journal of Physiology. Renal Physiology·Bruns A WattsDavid W Good
Aug 16, 2005·American Journal of Physiology. Regulatory, Integrative and Comparative Physiology·Ramiro JuncosJeffrey L Garvin
Aug 5, 2004·American Journal of Physiology. Renal Physiology·David W GoodGary E Shull
Jan 18, 2013·American Journal of Physiology. Renal Physiology·Bruns A WattsDavid W Good
Jul 4, 2003·American Journal of Physiology. Cell Physiology·David W GoodBruns A Watts
Apr 6, 2002·American Journal of Physiology. Renal Physiology·Pablo A Ortiz, Jeffrey L Garvin
Oct 19, 2004·Journal of Applied Physiology·Abolfazl K RadNick Ashton

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