title: Catecholamine secretion from digitonin-treated adrenal medullary chromaffin cells.
abstract: The plasma membrane of cultured chromaffin cells from bovine adrenal medulla was rendered leaky by incubation in low concentrations of digitonin. Digitonin (20 microM) induced Ca2+-dependent release of 10-20% of the catecholamine in the presence of 10 microM Ca2+ without addition of secretagogue. Half-maximal catecholamine release occurred at approximately 1 microM Ca2+ x Mg2+ could not substitute for Ca2+. Cells incubated with digitonin rapidly lost their ability to exclude trypan blue. Digitonin caused release of the cytosolic markers lactic dehydrogenase and phenylethanolamine-N-methyltransferase, but, in contrast to release of catecholamine, the release of the cytosolic proteins was inhibited by Ca2+. Soluble dopamine-beta-hydroxylase, a protein marker of granule contents, was released proportionally with catecholamine in a Ca2+ dependent manner. Catecholamine release was optimal in solutions containing MgATP. Hence, digitonin-treated cells, although they lose soluble cytosolic proteins and presumably low molecular weight cytosolic constituents, maintain the Ca2+-dependent reactions of exocytosis in the presence of MgATP. Digitonin-treated chromaffin cells may be a powerful system in which to study the biochemical mechanisms underlying exocytosis.
mesh_terms: D000313:Adrenal Medulla / Q000166:cytology* / Q000187:drug effects; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D002417:Cattle; D002837:Chromaffin Granules / Q000187:drug effects / Q000378:metabolism*; D002838:Chromaffin System / Q000378:metabolism*; D004072:Digitonin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005089:Exocytosis; D009638:Norepinephrine / Q000378:metabolism; D013997:Time Factors
chemical_list: D002217:Carbachol; D004072:Digitonin; D002118:Calcium; D009638:Norepinephrine