Regulation by pi and metabolic perturbations.
Nonaka, Tatsuya, David H. Warden, Kazumichi Matsushita, John B.
Stokes.
Laboratory of Epithelial Transport, Department of Internal
Medicine, University of Iowa College of Medicine and VA Medical
Center, Iowa City, IA 52242
APStracts 2:0119C, 1995.
We have previously demonstrated that the Na+-K+ pump on the
basolateral membrane of the rabbit cortical collecting duct can
function in the K+-K+ exchange mode. Increasing intracellular
phosphate in red blood cells inhibits the Na+ pump and increases K+
-K+ exchange. We found that maneuvers designed to increase
intracellular phosphate in collecting duct cells caused an increase
in K+-K+ exchange. Subjecting the cells to a metabolic insult
(cyanide) increased K+-K+ exchange by the pump as judged by its
ouabain sensitivity and lack of electrogenic or conductive
characteristics. The results demonstrate that the rate of K+-K+
exchange by the Na+-K+ pump can be altered by changes in
intracellular phosphate over a range that is physiologically or
pathologically achievable. The results also suggest a mechanism for
inhibition of vectorial Na+ transport during metabolic stress.
Received 21 April 1994; accepted in final form 13 January 1995.
APS Manuscript Number C218-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 10 March 1995.