Identification of P sub(2Y) purinoceptors associated with voltage-activated cation channels in cardiac ventricular myocytes of the rat

Extracellular ATP has vasodilatory and inotropic effects in the heart. We have demonstrated that extracellular ATP, in a concentration-dependent manner (10 nM - 0.1 mM), increased (Ca super(2+)) sub(i) in suspensions of isolated fura-2-loaded rat cardiac ventricular myocytes. The increase in (Ca sup...

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Bibliographic Details
Published in:	European journal of biochemistry Vol. 186; no. 1-2; pp. 395 - 404
Main Authors:	Bjoernsson, O G, Monck, J R, Williamson, J R
Format:	Journal Article
Language:	English
Published:	01-01-1989
Subjects:	cations ventricles
Online Access:	Get full text
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Summary:	Extracellular ATP has vasodilatory and inotropic effects in the heart. We have demonstrated that extracellular ATP, in a concentration-dependent manner (10 nM - 0.1 mM), increased (Ca super(2+)) sub(i) in suspensions of isolated fura-2-loaded rat cardiac ventricular myocytes. The increase in (Ca super(2+)) sub(i) was often biphasic, with an initial fast phase of low amplitude, followed by a slower phase of higher amplitude. A second application of ATP had little effect, and ATP abolished the effect of subsequent electrical stimulations, even through the cells were still able to respond with an increase in (Ca super(2+)) sub(i) to KCl-induced depolarization or stimulation by caffeine. The data are consistent with the presence of purinoceptors (P sub(2Y) subtype) on the sarcolemma of cardiac ventricular myocytes of the rat, which upon activation lead to depolarization and activation of cation channels of the sarcolemma and flux of extracellular Ca super(2+) into the cells. This may result in further flux of Ca super(2+) into the cytosol from intracellular stores. The effects of extracellular ATP on (Ca super(2+)) sub(i) in rat cardiac ventricular myocytes may, in part, explain the direct inotropic effects of extracellular ATP on the mammalian heart.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 content type line 23 ObjectType-Feature-1
ISSN:	0014-2956