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

The effects of leucine- and methionine-enkephalin, opiate peptides, on Ca2 efflux from cultured bovine adrenal chromaffin cells were examined. These enkephalins stimulated the efflux of Ca-45(2+) from cells in a concentratio n-dependent manner (10(-8)M - 10(-6)M). Leucine-enkephalin did not increase the intracellular free Ca2+ level, Ca-45(2+) uptake, catecholamine secreti on, cAMP level or cGMP level. The peptide-stimulated Ca-45(2+) efflux was n ot inhibited by incubation in Ca2+-free medium, but was inhibited by incuba tion in Na+-free medium. These results indicate that enkephalins stimulate extracellular Na+-dependent 45Ca2+ efflux from cultured bovine adrenal chro maffin cells, probably by stimulating membrane Na+/Ca2+ exchange. (C) 1999 Elsevier Science Inc.