K-depletion modifies the properties of sch 28080-sensitive k-atpase
in rat collecting duct.
B, Buffin-Meyer, M. Younes-Ibrahim, C. Barlet-Bas, L. Cheval, S.
Marsy, and A. Doucet.
Laboratoire de Biologie Int[umlaut]agr[umlaut]ae des Cellules
R[umlaut]anales, Service de Biologie Cellulaire, CEA Saclay,
Unit[umlaut]a 1859 associ[umlaut]ae au CNRS
APStracts 3:0187F, 1996.
Two distinct SCH 28080-sensitive K-ATPases were previously described
in the rat nephron : a ouabain-resistant K-ATPase (type I) present in
collecting ducts (CD) and a ouabain-sensitive form (type II) located
in proximal tubules (PT) and thick ascending limbs (TAL). In K
-depleted rats, K-ATPase activity is increased in CD whereas it is
reduced in PT and TAL. Because expression of colonic H,K-ATPase is
restricted to the CD of K-depleted rats, we hypothesized that K
-ATPase from the CD of K-depleted rats might be different from types I
and II. And indeed, type III K-ATPase displays higher sensitivities
to ouabain and to SCH 28080 than type II, a lower sensitivity to SCH
28080 than type I, and, conversely to types I and II, it can be
stimulated by Na+. Pharmacological differences between types II and
III K-ATPases were confirmed by 3H-ouabain binding experiments. Thus,
the rat kidney expresses three K-ATPases that differ by their
pharmacological and kinetical properties, their distribution profile
along the nephron and their behaviour during potassium depletion.
Received 24 April 1996; accepted in final form 3 October 1996.
APS Manuscript Number F124-6.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996