Transmembrane chloride currents in human atrial myocytes.
Li, Gui-Rong, Jianlin Feng, Zhiguo Wang, and Stanley Nattel.
Department of Medicine, Montreal Heart Institute and University of
Montreal, and the Department of Pharmacology, McGill University,
Montreal, Quebec H1T 1C8, Canada
APStracts 2:0421C, 1995.
The present study was designed to evaluate the presence of basal,
swelling-induced, and cyclic AMP-dependent Cl- currents in human
atrial myocytes studied with the whole-cell patch clamp technique.
Under basal conditions, a small outwardly-rectifying background
conductance was noted, that reversed close to 0 mV and was not
altered by Cl- replacement. Isoproterenol (1?[mu]M), forskolin (3
[mu]M) and 8-bromo-cyclic AMP (50 [mu]M) did not increase membrane
conductance, even when responsiveness to isoproterenol was confirmed
by an increase in ICa and when perforated-patch techniques (nystatin)
were used. Exposure to hyposmotic solutions increased cell volume and
induced a whole-cell conductance that showed outward rectification,
was inhibited by 4-acetamido-4_-isothiocyanatostilbene
-2,2_disulphonic acid (DIDS, 100 [mu]M), and responded to changes in
Cl- gradient in a fashion consistent with a Cl--selective conductance
with estimated relative permeabilities of 1, 0.25 and 0.07 for Cl-,
methanesulphonate and aspartate respectively. The results suggest
that human atrial cells lack basal and cyclic adenosine
monophosphate-dependent Cl- current, but manifest a substantial Cl-
conductance in the presence of cell swelling.
Received 31 January 1995; accepted in final form 8 August 1995.0
APS Manuscript Number C57-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 December 95