AJP - Renal Physiology, Vol 259, Issue 6 902-F909, Copyright © 1990 by American Physiological Society

ARTICLES

Cell pH regulation in rabbit outer medullary collecting duct cells: mechanisms of HCO3(-)-independent processes

M. Kuwahara, S. Sasaki and F. Marumo
Second Department of Internal Medicine, Tokyo Medical and Dental University, Japan.

To clarify mechanisms of intracellular pH (pHi) regulation in outer stripe of outer medullary collecting duct (OMCDOS), isolated perfused OMCDOS of the rabbit were loaded with 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein (BCECF), and single cell pHi was monitored by an image processing system. Initial pHi recovery rates (dpHi/dt, pH unit/s x 10(3)) after intracellular acid load made by NH4Cl prepulse were determined. In the absence of exogenous CO2-HCO3-, dpHi/dt was 12.3 +/- 0.9 (means +/- SE) in principal cells (PC), and 11.5 +/- 1.0 in intercalated cells (IC). In PC, total ambient Na+ removal halted pHi recovery (dpHi/dt = 0.6 +/- 0.5), and pHi recovered when Na+ was added to the basolateral (dpHi/dt = 14.7 +/- 0.8) but not to the luminal (dpHi/dt = 0.9 +/- 0.5) solutions. This bath Na+ effect was amiloride inhibitable. In IC, pHi recovered (dpHi/dt = 6.4 +/- 0.3) in the absence of ambient Na+. This pHi recovery was significantly reduced by luminal 0.5 mM N-ethylmaleimide (NEM) or 0.5 mM N,N'-dicyclohexylcarbodiimide (DCCD). Basolateral NEM or DCCD had no significant effect. Basolateral addition of Na+ significantly accelerated the pHi recovery. These data suggest the presence of basolateral Na(+)-H+ exchange in both PC and IC, and luminal NEM- and DCCD-sensitive H+ pump in IC of rabbit OMCDOS.

This article has been cited by other articles:

				S. Muto Potassium Transport in the Mammalian Collecting Duct Physiol Rev, January 1, 2001; 81(1): 85 - 116. [Abstract] [Full Text] [PDF]

				A. M. Weinstein A mathematical model of the outer medullary collecting duct of the rat Am J Physiol Renal Physiol, July 1, 2000; 279(1): F24 - F45. [Abstract] [Full Text] [PDF]