Stimulatory effect of enkephalins on calcium efflux from bovine adrenal chromaffin cells in culture

Abstract The effects of leucine- and methionine-enkephalin, opiate peptides, on Ca 2+ efflux from cultured bovine adrenal chromaffin cells were examined. These enkephalins stimulated the efflux of 45 Ca 2+ from cells in a concentration-dependent manner (10 −8 M − 10 −6 M). Leucine-enkephalin did not increase the intracellular free Ca 2+ level, 45 Ca 2+ uptake, catecholamine secretion, cAMP level or cGMP level. The peptide-stimulated 45 Ca 2+ efflux was not inhibited by incubation in Ca 2+ -free medium, but was inhibited by incubation in Na + -free medium. These results indicate that enkephalins stimulate extracellular Na + -dependent 45 Ca 2+ efflux from cultured bovine adrenal chromaffin cells, probably by stimulating membrane Na + /Ca 2+ exchange.