Elevated potassium stimulates enkephalin biosynthesis in bovine chromaffin cells

Exposure of bovine adrenal medullary cells in culture to a depolarizing concentration of potassium (50 mM), causes a rapid rise in both cellular and secreted Met-enkephalin peptide. The induction of peptide is preceded by the appearance of a nuclear preproenkephalin transcript and subsequent increases in cytoplasmic preproenkephalin mRNA. These data suggest that the depolarizing medium acts by enhancing enkephalin gene transcription. Potassium stimulation of Met-enkephalin biosynthesis requires the presence of extracellular Ca2+ and is not observed in either low Ca2+ medium or in the presence of D600, a Ca2+ channel blocker. As similar depolarizing stimuli inhibit enkephalin biosynthesis in the rat adrenal gland, these findings suggest that the regulation of enkephalin peptide content in neuroendocrine cells is highly species specific.