Up-regulation of h+-atp ase in the distal nephron during potassium
depletion: structural and functional evidence..
Bailey, Matthew A., Robert M. Fletcher, David F. Woodrow, Robert J.
Unwin, Stephen J. Walter.
1Centre for Nephrology, Department of Medicine, The Rayne
Institute, University College London, 5 University Street, WC1E 6JJ;
2Department of Histopathology, Division of Investigative Science and
3Division of Biomedical Sciences, Imperial College School of
Medicine, Charing Cross Hospital, London, W6 8RF, United Kingdom.
APStracts 5:0148F, 1998.
In the present study we have investigated the effects of dietary
potassium depletion on the activity and distribution of the H+-ATPase
in the distal nephron of the Sprague-Dawley rat. H}f5+-ATPase
activity was assessed from the change in transepithelial potential
difference (Vte) in response to bafilomycin A1 during perfusion of
the late distal tubule in vivo, with solutions containing inhibitors
of known ion channels. Bafilomycin A1 caused a negative deflection in
Vte in control animals, an effect that was significantly enhanced
during potassium depletion (P<0.01). The distribution of H+-ATPase
within the population of intercalated cells was assessed using a
specific monoclonal antibody (E11). Hypokalemia was associated with a
highly significant redistribution of the staining pattern
(P<0.001), with an increase in the percentage of cells displaying
immunoreactivity in the apical membrane. These results indicate that
dietary potassium depletion increases electrogenic H+-ATPase activity
in the rat distal tubule; this may be associated with increased
insertion of pumps into the apical membrane.
Received 5 May 1998; accepted in final form 20 August 1998.
APS Manuscript Number F105-8.
Article publication pending Am. J. Physiol. (Renal Physiology).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 21 September 1998