APStracts 2:0040F, 1995.

Function and Structure of H,K-ATPase in the Kidney. Wingo, Charles S., and Adam J. Smolka. Laboratory of Epithelial Transport, Division of Nephrology, Hypertension and Transplantation, Department of Internal Medicine and Department of Physiology, University of Florida, and the Nephrology and Hypertension Section, Veterans Affairs Medical Center, Gainesville, FL 32608-1197, and Division of Gastroenterology, Department of Medicine, Medical University of South Carolina, Charleston, SC 29425-2223

APStracts 2:0040F, 1995.

The present review summarizes recent functional and structural evidence indicating that the kidney possesses at least one and probably more than one isoform of a proton and potassium-activated adenosinetriphosphatase (H,K-ATPase). Functional studies have examined in detail the mechanism of luminal acidification and potassium (K)/rubidium (Rb) absorption by the outer medullary collecting duct (CD) from the inner stripe, a high capacity distal site of urinary acidification. These studies indicate that the mechanism of proton secretion in this segment is similar to a model proposed for gastric acid secretion. Specifically, the profound effect of H,K-ATPase inhibitors or luminal K removal on net bicarbonate (HCO3) absorption indicates a major role for an H,K pump in luminal acidification by the outer medullary CD. The importance of an H,K-ATPase is further supported by the finding that nanomolar concentrations of bafilomycin A1, which specifically inhibit vacuolar-type H-ATPase, have significantly smaller effects on net HCO3 absorption than do H,K-ATPase inhibitors. Studies on the perfused inner medullary collecting duct (IMCD) and cultured IMCD cells also suggest a significant role for H,K-ATPase in luminal acidification by the IMCD.

Received 10 March 1995; accepted in final form 20 March 1995.
APS Manuscript Number F103-5.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on  4 April 1995.