Regulatory mechanism of calcium efflux from cultured bovine adrenal chromaffin cells induced by extracellular ATP

Abstract The effect of adenosine-5′-triphosphate (ATP) on Ca 2+ efflux from cultured bovine adrenal chromaffin cells 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), α,β-methylene-ATP and adenosine-5′-diphosphate (ADP), but was not by adenosine-5′-monophosphate (AMP) and adenosine. The ATP-stimulated 45 Ca 2+ efflux was not affected by deprivation of the extracellular Ca 2+ and Mg 2+ , but was dependent on the extracellular Na + concentrations. ATP increased the influx of 22 Na + into the cells. These results indicate tthat ATP stimulates extracellular Na + -dependent 45 Ca 2+ efflux from cultured bovine adrenal chromaffin cells, probably through its stimulatory effect on membrane Na + Ca 2+ exchange.