STIMULATORY EFFECT OF ANGIOTENSIN-II ON CALCIUM EFFLUX FROM CULTURED BOVINE ADRENAL CHROMAFFIN CELLS

The effect of angiotensin II on Ca2+ mobilization in cultured bovine adrenal chromaffin cells was examined. Angiotensin II (10(-7)M) increased the intracellular free Ca2+ level ([Ca2+](i)) to a peak in the presence or absence of extracellular Ca2+, followed by decrease with time. Angiotensin II (10(-9) - 10(-6)M) also stimulated Ca-45(2+) efflux from cultured bovine adrenal chromaffin cells in a concentration-dependent manner. Its stimulatory effect on Ca-45(2+) efflux was inhibited by the angiotensin II antagonist [Sar(1), IIe(8)]-angiotensin II or [Sar(1), Val(5), Ala(8)]-angiotensin II. The increase in angiotensin II-stimulated Ca-45(2+) efflux was dependent on the extracellular Naf concentration. Angiotensin II also increased Na-22(+) influx into the cells. These results indicate that stimulation of the angiotensin II receptor induces extracellular Na+-dependent Ca2+ efflux from cultured bovine adrenal chromaffin cells, probably by acceleration of Na+/Ca2+ exchange.