Arkhammar P, Nilsson T, Berggren P O
Biochim Biophys Acta. 1986 Jul 11;887(2):236-41. doi: 10.1016/0167-4889(86)90060-1.
The effects of 12-O-tetradecanoylphorbol 13-acetate (TPA) on the handling of Ca2+ and insulin release were investigated in the clonal insulin-producing cell line RINm5F. The presence of the phorbol ester lowered the free cytoplasmic Ca2+ and suppressed the increase obtained by depolarization with high concentrations of K+. Despite the lowering in cytoplasmic Ca2+ by TPA, there was a concomitant stimulation of insulin release indicating that one feature of protein kinase C activation is to make the secretory system more sensitive to Ca2+. Furthermore, there was no interaction of TPA with the mechanisms responsible for inositol 1,4,5-tris(phosphate) induced Ca2+ release or Ca2+ uptake in permeabilized cells. Although TPA slightly depolarized the RINm5F cells there was no interference with K+-induced depolarization. It is suggested that an additional effect of protein kinase C activation in these cells, is to stimulate the extrusion of Ca2+ over the plasma membrane.
在克隆的胰岛素分泌细胞系RINm5F中，研究了12 - O - 十四烷酰佛波醇13 - 乙酸酯（TPA）对钙离子处理及胰岛素释放的影响。佛波酯的存在降低了细胞质游离钙离子水平，并抑制了高浓度钾离子去极化所引起的钙离子增加。尽管TPA使细胞质钙离子水平降低，但同时却刺激了胰岛素释放，这表明蛋白激酶C激活的一个特点是使分泌系统对钙离子更敏感。此外，在通透细胞中，TPA与负责肌醇1,4,5 - 三磷酸诱导的钙离子释放或钙离子摄取的机制之间没有相互作用。虽然TPA使RINm5F细胞轻微去极化，但对钾离子诱导的去极化没有干扰。提示在这些细胞中蛋白激酶C激活的另一个作用是刺激钙离子通过质膜排出。
