Effect of extracellular adenosine 5′-triphosphate on Ca2+ efflux from freshly isolated adult rat cardiomyocytes

Abstract The effect of extracellular adenosine 5′-triphosphate (ATP) on Ca 2+ efflux from freshly isolated adult rat cardiomyocytes was examined. ATP stimulated the efflux of 45 Ca 2+ from the cells in a concentration-dependent manner (0.01–1 mM). The 45 Ca 2+ efflux from the cells was also stimulated by adenosine-5′-O-(3-thiotriphosphate) (ATP-γs) and α,β-methylene-ATP and adenosine 5′-diphosphate, but not by adenosine 5′-monophosphate and adenosine. The ATP-stimulated 45 Ca 2+ efflux was not affected by deprivation of the extracellular Ca 2+ , but was dependent on the presence of extracellular Na + . These results indicate that ATP stimulates extracellular Na + -dependent 45 Ca 2+ efflux from freshly isolated adult rat cardiomyocytes, probably through its stimulatory effect on the plasma membrane P 2 purinoceptors which may couple to Na + /Ca 2+ exchange.