Calcium-activated chloride currents in primary cultures of rabbit
distal convoluted tubule..
Bidet, M., M. Tauc, I. Rubera, G De Renzis, C. Poujeol, M. T. Bohn,
and P. Poujeol.
URA CNRS 1938, Universit[acute]e de Nice Sophia Antipolis, Parc
Valrose 06108 Nice Cedex 2, France
APStracts 3:0116F, 1996.
Chloride (Cl-) conductances were studied in primary cultures of rabbit
distal convoluted tubule (DCTb) by the whole cell patch clamp
technique. We identified a Cl- current activated by 2 [mu]M
extracellular ionomycin. The kinetics of the macroscopic current were
time-dependent for depolarizing potentials with a slow developing
component. The steady-state current presented outward rectification
and the ion selectivity sequence was I-> Br->>Cl
->glutamate. The current was inhibited by 0.1 mM NPPB, 1 mM DIDS
and 1 mM DPC. To identify the location of the Cl- conductance, SPQ
fluorescence experiments were carried out in confluent cultures
developed on collagen-coated permeable filters. Cl- removal from the
apical solution induced a Cl- efflux which was stimulated by 10 [mu]M
forskolin. Forskolin had no effect on the basolateral Cl-
permeability. Cl- substitution in the basolateral solution induced an
efflux stimulated by 2 [mu]M ionomycin or 50 [mu]M extracellular ATP.
Ionomycin had no effect on the apical Cl- fluxes. Thus cultured DCTb
cells exhibit Ca++ -activated Cl- channels located in the basolateral
membrane. This Cl- permeability was active at a resting membrane
potential and could participate in the Cl- reabsortion across the
DCTb in control conditions.
Received 6 February 1996; accepted in final form 14 May 1996.
APS Manuscript Number F38-6.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 25 July 1996