G protein regulation of cardiac muscarinic potassium channel.
Kurachi, Yoshihisa.
Department of Pharmacology II, Faculty of Medicine, Osaka
University
APStracts 2:0128C, 1995.
Several ion channels can be regulated by G proteins in a
$QUOTmembrane-delimited$QUOT manner. The cardiac muscarinic K+ (KACh)
channel, which is responsible for the acetylcholine or adenosine-
induced deceleration of heart beat and atrioventricular conduction,
is the prototype of this type of receptor-dependent regulation of ion
channels. Since similar transduction mechanisms are utilized by
various membrane receptors, such as somatostatin, 5HT-1,, [alpha]2
-adrenergic, [mu] and d opioid, D2-dopamine and GABAB receptors, in
neuronal, hormone-secreting, renal or smooth muscle cells, the G
protein (GK)-KACh channel system illustrates the principles
underlying one of the most important cell signalling mechanisms [17].
It seems that both [alpha] and bg subunits of GK may be involved in
the regulation of the KACh channel of mammalian atrial muscle. A
general consensus of opinion has emerged, after some years of
controversy, to spport the notion that physiological activation of
the channel by GK is the responsibility of the bg subunits. Recent
evidince suggests that the KACh channel interacts with the [alpha]
subunit in the terminating process of activation.
Received 2 August 1994; accepted in final form 9 February 1995.
APS Manuscript Number C447-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 10 March 1995.