APStracts 2:0156F, 1995.

Effects of chronic hypokalemia on renal expression of the "gastric" h+-k+-atpase [alpha] subunit gene. Ahn, Kyu Y., Paula B. Turner, Kirsten M. Madsen, and Bruce C. Kone. Departments of Internal Medicine and Integrative Biology, The University of Texas Health Science Center at Houston, Houston, TX 77030, Department of Anatomy, Chonnam National University Medical School, Kwangju, Korea 501-190, and Department of Medicine, University of Florida College of Medicine, Gainesville, FL 32610 -0224

APStracts 2:0156F, 1995.

Effects of Chronic Hypokalemia on Renal Expression of the "Gastric" H+-K+-ATPase [alpha] Subunit Gene. Chronic potassium restriction leads to active potassium reabsorption in the late distal nephron and collecting duct, segments known to express gastric H+-K+-ATPase [alpha] subunit mRNA. In this study, the cellular distribution and relative abundance of mRNA encoding this isoform were examined in kidneys of normal and potassium-deprived (two weeks) rats. In situ hybridization with isoform-specific cRNA probes demonstrated prominent expression of this gene in the connecting segment (CNT), entire collecting duct, and renal papillary surface epithelium in a comparable distribution in both groups of rats. Hypertrophy of the outer medullary collecting ducts in the inner stripe of potassium-restricted rats was observed. Competitive PCR analysis revealed two-fold greater levels of gastric H+-K+- ATPase [alpha] subunit mRNA (normalized to the level of [beta]-actin mRNA) in the cortex, but roughly comparable levels in the outer and inner medulla, of potassium-restricted rats compared to controls. These data suggest that chronic potassium restriction results in modestly enhanced renal cortical expression of the gastric H+-K+ -ATPase [alpha] subunit gene, and that this isoform may participate in potassium conservation by the CNT and cortical collecting duct during potassium deprivation.

Received 7 December 1994; accepted in final form 21 August 1995.
APS Manuscript Number F435-4.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 September 1995.