title: Effect of calmidazolium and phorbol ester on catecholamine secretion from adrenal chromaffin cells.
abstract: Carbamylcholine-stimulated catecholamine release from adrenal chromaffin cells was completely inhibited by pretreatment of the cells for 10 min with 1 microM calmidazolium. Catecholamine release due to 55 mM K+ and ionophore A23187 was also inhibited by calmidazolium but less effectively than release due to carbamylcholine. Inhibition of release appeared to be due to an effect of calmidazolium on a step distal to Ca2+ entry, since the carbamylcholine-stimulated rise in the concentration of intracellular free calcium, monitored using quin-2, was unaffected by calmidazolium. The possibility was considered that calmidazolium inhibited secretion through an effect on protein kinase C rather than calmodulin. However, the phorbol ester, 12-O-tetradecanoylphorbol 13-acetate (TPA), had no demonstrable effect on catecholamine release, arguing against a significant role for protein kinase C in secretion from adrenal chromaffin cells. These results give further support to the notion that calmodulin plays a role in the secretory process in chromaffin cells.
mesh_terms: D000313:Adrenal Medulla / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D002395:Catecholamines / Q000378:metabolism*; D002417:Cattle; D002837:Chromaffin Granules / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology*; D007700:Kinetics; D010704:Phorbols / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
chemical_list: D002395:Catecholamines; D004791:Enzyme Inhibitors; D007093:Imidazoles; D010704:Phorbols; D000001:Calcimycin; C031938:calmidazolium; D002217:Carbachol; D013755:Tetradecanoylphorbol Acetate; D011188:Potassium