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pHi regulation in frog retinal pigment epithelium: two apical membrane mechanisms

pHi regulation in frog retinal pigment epithelium: two apical membrane mechanisms LIN, HAI, AND SHELDON S. MILLER. p& regulation in frog retinal pigment epithelium: two apical membrane mechanisms. Am. J. Physiol. 261 (Cell Physiol. 30): C132-C142,1991.-This study demonstrates that the apical membrane of frog retinal pigment epithelium (RPE) contains two intracellular pH (pHi) regulatory mechanisms, an electrogenic Na-HC03 cotransporter blocked by DIDS and an amiloride-inhibitable Na-H antiporter. pHi was studied using the pH-sensitive dye 2’,7’bis(2-carboxyethyl)-5,6-carboxyfluorescein (BCECF). In these cells resting pHi equals 7.26 t 0.09 (n = 58). After an acid load (NH&l prepulse), pHi recovery required apical extracellular Na concentration ([Na],) in HCO.? or HCO,?-free Ringer. In HCOs Ringer recovery was completely blocked by 1 mM apical DIDS (n = 5) but was not affected by absence of Cl. In HCO3free Ringer, recovery was completely blocked by 1 mM apical amiloride (n = 3). At resting pHi7 the intrinsic pH-buffering as capacity of the cell is ~7.1 mM/pH and rises monotonically pHi decreases. In HCO.? Ringer, the initial rate of acidification caused by apical Na removal, 0.39 t 0.03 pH/min (n = 26), was 80-90% inhibited by apical DIDS (n = 5) and 16% inhibited by 1 mM apical amiloride (n = 7), but not affected by absence http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png AJP - Cell Physiology The American Physiological Society

pHi regulation in frog retinal pigment epithelium: two apical membrane mechanisms

H. Lin and S. S. Miller
AJP - Cell Physiology , Volume 261: C132 – Jul 1, 1991
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Publisher
The American Physiological Society
Copyright
Copyright © 1991 the American Physiological Society
ISSN
0363-6143
eISSN
1522-1563
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Abstract

LIN, HAI, AND SHELDON S. MILLER. p& regulation in frog retinal pigment epithelium: two apical membrane mechanisms. Am. J. Physiol. 261 (Cell Physiol. 30): C132-C142,1991.-This study demonstrates that the apical membrane of frog retinal pigment epithelium (RPE) contains two intracellular pH (pHi) regulatory mechanisms, an electrogenic Na-HC03 cotransporter blocked by DIDS and an amiloride-inhibitable Na-H antiporter. pHi was studied using the pH-sensitive dye 2’,7’bis(2-carboxyethyl)-5,6-carboxyfluorescein (BCECF). In these cells resting pHi equals 7.26 t 0.09 (n = 58). After an acid load (NH&l prepulse), pHi recovery required apical extracellular Na concentration ([Na],) in HCO.? or HCO,?-free Ringer. In HCOs Ringer recovery was completely blocked by 1 mM apical DIDS (n = 5) but was not affected by absence of Cl. In HCO3free Ringer, recovery was completely blocked by 1 mM apical amiloride (n = 3). At resting pHi7 the intrinsic pH-buffering as capacity of the cell is ~7.1 mM/pH and rises monotonically pHi decreases. In HCO.? Ringer, the initial rate of acidification caused by apical Na removal, 0.39 t 0.03 pH/min (n = 26), was 80-90% inhibited by apical DIDS (n = 5) and 16% inhibited by 1 mM apical amiloride (n = 7), but not affected by absence

Journal

AJP - Cell Physiology – The American Physiological Society

Published: Jul 1, 1991

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