Serotonin increases Na+-dependent Ca2+ efflux from bovine adrenal chromaffin cells in culture

Abstract The effect of serotonin (5-hydroxytryptamine, 5-HT) on Ca 2+ mobilization in bovine adrenal chromaffin cells in culture was examined. 5-HT (10 −5 M) did not increase secretion of catecholamine, uptake of 45 Ca 2+ and levels of intracellular free Ca 2+ ([Ca 2+ ] i ). However, 5-HT (10 −8 –10 −5 M) stimulated the efflux of 45 Ca 2+ from cultured bovine adrenal chromaffin cells in a concentration-dependent manner. Its stimulatory effect on 45 Ca 2+ efflux was inhibited by cyproheptadine (a 5-HT 1A and 5-HT 2 receptor antagonist) or mianserin (a 5-HT 2 receptor antagonist). The increase in 5-HT-stimulated 45 Ca 2+ efflux was dependent on extracellular Na + concentration, but not extracellular Ca 2+ concentration. These results indicate that stimulation of the 5-HT receptors induces extracellular Na + -dependent Ca 2+ efflux from bovine adrenal chromaffin cells in culture, probably by acceleration of Na + /Ca 2+ exchange.