title: Differential effects of protein kinase C activators on carbamylcholine- and high K+-induced rises in intracellular free calcium concentration in cultured adrenal chromaffin cells.
abstract: Pretreatment of adrenal chromaffin cells with protein kinase C activators, i.e. 12-O-tetradecanoyl phorbol-13-acetate (TPA) and 1-oleoyl 2-acetyl glycerol (OAG), partially inhibited carbamylcholine (CCh)-induced rise in intracellular free Ca2+ concentration ([Ca2+]i). The apparent IC50 values of TPA and OAG were 3 nM and 25 microM, respectively. The effect of TPA on the CCh-induced rise in [Ca2+]i was overcome by pretreatment of the cells with a protein kinase C inhibitor, 1-(5-isoquinidinesulfonyl)-2-methylpiperazine hydrochloride (H-7). In contrast, KCl-induced rise in [Ca2+]i was not affected by pretreating the cells with TPA or OAG. An inactive phorbol ester, 4 alpha-phorbol 12,13-didecanoate failed to affect the CCh-induced rise in [Ca2+]i. CCh-induced 45Ca2+ uptake was also partially inhibited by pretreatment of the cells with TPA or OAG, but KCl-induced 45Ca2+ uptake was not affected by these pretreatments. These results indicate that protein kinase C activation causes an uncoupling of signal transduction between the nicotinic receptors and Ca2+ channels.
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000311:Adrenal Glands / Q000166:cytology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology*; D002417:Cattle; D002837:Chromaffin Granules / Q000378:metabolism*; D002838:Chromaffin System / Q000378:metabolism*; D004075:Diglycerides / Q000494:pharmacology; D004789:Enzyme Activation; D007546:Isoquinolines / Q000494:pharmacology; D007700:Kinetics; D010879:Piperazines / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology*; D011189:Potassium Chloride / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D004075:Diglycerides; D007546:Isoquinolines; D010879:Piperazines; D011189:Potassium Chloride; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; C038237:1-oleoyl-2-acetylglycerol; D002217:Carbachol; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D011188:Potassium; D002118:Calcium