Modulation of atp-sensitive k+ channels in rabbit ventricular
myocytes by adenosine a1 receptor activation.
Kim, Euiyong, Jin Han, Wonkyung Ho, Yung E Earm.
Department of Physiology & Biophysics, College of Medicine, Inje
University, Seoul National University, Korea
APStracts 3:0352H, 1996.
The objective of the present study was to characterize the role of
adenosine in the regulation of KATP channel activity in isolated
rabbit ventricular myocytes using the patch clamp technique. In an
outside-out patch exposed to GTP and ATP at the intracellular
surface, external adenosine stimulated KATP channel activity. In an
inside-out patch exposed to external adenosine, ATP reduced KATP
channel activity, and GTP stimulated KATP channel activity. GTP[tau]S
resulted in a gradual increase of KATP channel activity even in the
absence of adenosine. When myocytes were preincubated with either
pertussis toxin or 8-cyclopentyl-1,3-dipropylxanthine, adenosine A1
receptor activation failed to activate KATP channel. Analysis of the
open and closed time distributions showed that adenosine A1 receptor
activation increased burst duration and decreased interburst
duration. In dose-response relationship for ATP, adenosine A1
receptor activation shifted the half-maximal inhibition of KATP
channel from 70 to 241 [mu]M.
Received 14 December 1995; accepted in final form 30 July 1996.
APS Manuscript Number H1164-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 29 August 1996