Regulation of h+, k+-atpase expression in kidney.
Dubose, Thomas D., Jr, Juan Codina, Afroz Burges, and Thomas A.
Pressley.
Departments of Medicine, Physiology and Cell Biology, University of
Texas -Houston Medical School, Houston, TX
APStracts 2:0079F, 1995.
It is now widely accepted that proton secretion by the collecting duct
is mediated, in part, by an H+,K+-ATPase. Controversy persists
regarding which H+,K+-ATPase isoform is expressed in kidney. Several
laboratories have reported preliminarily the amplification from
kidney of stomach and/or colon-identical products using gastric or
colonic-specific primers in the polymerase chain reaction. We have
developed highly specific probes for the catalytic subunit using RT
-PCR with gastric- or colonic-specific primers. The resulting cDNA's
were verified by sequencing and were then used in Northern analysis
of whole kidney total RNA obtained from one of three groups of rats:
1) controls, 2) chronic hypokalemia, or 3) chronic metabolic
acidosis. Probes for both the colonic and gastric [alpha] H+,K+
-ATPase isoforms hybridized to whole kidney total RNA derived from
potassium replete control rats. A marked elevation of colonic mRNA
abundance, but not gastric message, was observed in response to
chronic hypokalemia induced by dietary potassium deprivation.
Elevation of either gastric or colonic mRNA was not observed with
chronic metabolic acidosis. Under the conditions of the present
study, it appears that the mRNA encoding the colonic isoform of the
[alpha] H+,K+-ATPase in kidney is up-regulated by chronic
hypokalemia, but not by chronic metabolic acidosis. The observation
that the gastric [alpha] H+,K+-ATPase isoform does not appear to be
regulated in either condition, suggests that this isoform is
expressed constitutively in kidney.
Received 13 December 1994; accepted in final form 11 April 1995.
APS Manuscript Number F440-4.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 26 May 1995.