Role of Ca2+/phospholipid-dependent protein kinase in catecholamine secretion from bovine adrenal medullary chromaffin cells.
The role of Ca2+/phospholipid-dependent protein kinase (protein kinase C) in catecholamine secretion from bovine adrenal medullary chromaffin cells was examined using four protein kinase C inhibitors: polymyxin B, sphingosine, staurosporine, and 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7). For this purpose, digitonin-permeabilized chromaffin cells were used. Secretion of catecholamines from these cells was stimulated by the addition of micromolar amounts of exogenous free Ca2+. 12-O-Tetradecanoylphorbol-13-acetate (TPA) and arachidonic acid, activators of protein kinase C, enhanced the catecholamine secretion evoked by Ca2+. But phorbol-12, 13-diacetate, a phorbol ester analog that does not activate protein kinase C, had no effect on Ca2(+)-evoked secretion. Polymyxin B at a low concentration (1 microM) abolished the enhancement of secretion by TPA or arachidonic acid without affecting the secretion evoked by Ca2+. However, polymyxin B at higher concentrations (10-100 microM) greatly reduced Ca2+-evoked catecholamine secretion. Sphingosine 10 microM-1 mM), Staurosporine (100 nM-1 microM, and H-7 (100-500 microM) inhibited TPA- or arachidonic acid-enhanced secretion but not Ca2(+)-evoked secretion. In cells in which protein kinase C was down-regulated by TPA, specific binding of [3H]phorbol-12,13-dibutyrate to the cells almost disappeared and the enhancement of secretion by TPA was no longer observed, whereas Ca2(+)-evoked secretion was maintained. These results strongly suggest that protein kinase C is not essential for the Ca2(+)-dependent catecholamine secretion from bovine adrenal chromaffin cells, but acts instead as a modulator.
Tachikawa
E
E
Department of Pharmacology, School of Medicine, Iwate Medical University, Morioka, Japan.
Takahashi
S
S
Kashimoto
T
T
Kondo
Y
Y
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000313:Adrenal Medulla / Q000187:drug effects / Q000378:metabolism*; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002395:Catecholamines / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured / Q000187:drug effects; D004072:Digitonin / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects; D004759:Enterochromaffin Cells / Q000378:metabolism; D007546:Isoquinolines / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D011112:Polymyxin B / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D013110:Sphingosine / Q000494:pharmacology; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000470:Alkaloids; D001095:Arachidonic Acids; D002395:Catecholamines; D007546:Isoquinolines; D010879:Piperazines; D016718:Arachidonic Acid; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D011493:Protein Kinase C; D019311:Staurosporine; D011112:Polymyxin B; D004072:Digitonin; D013110:Sphingosine; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium