Electrophysiological and functional effects of adenosine on
ventricular cardiomyocytes of various mammalian species.
Song, Yejia, and Luiz Belardinelli.
Department of Medicine, University of Florida Medical School,
Gainesville, Florida 32610, USA
APStracts 3:0128C, 1996.
The goal of this study was to determine the electrophysiological and
functional effects of adenosine on ventricular myocytes of guinea
pig, rabbit, rat and ferret hearts. Adenosine (100 [mu]M) shortened
the action potential durations of rat and ferret myocytes by 14+/-1%
and 57+/-7%, reduced the amplitudes of cell twitch shortening by
13+/-1% and 54+/-5%, and increased outward currents by 15+/-4% and
55+/-5%, respectively, but had no effect on guinea pig and rabbit
myocytes. The properties of adenosine-activated outward current in
rat and ferret ventricular myocytes indicated that this current is
the adenosine-sensitive K+ current, IK(Ado). Adenosine had no
significant effect on basal Ca2+ current, but specifically inhibited
isoproterenol-stimulated L-type Ca2+ current in myocytes of all
species studied. Binding studies revealed that the density of A1
adenosine receptors (A1AdoR) was highest in ferret and lowest in
rabbit myocytes, but the differential effects of adenosine among
species could not be solely explained by differences in A1AdoR
density. In summary, adenosine shortened the action potential and
reduced the twitch shortening of rat and ferret, but not of guinea
pig and rabbit ventricular myocytes. Shortening of the action
potential was associated with the activation of IK(Ado). The anti
-[beta]-adrenergic action of adenosine appeared to be independent of
species.
Received 13 December 1995; accepted in final form 9 April 1996.
APS Manuscript Number C745-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 1 May 96