Barthelson R A, Jacoby D B, Widdicombe J H
Department of Physiology, University of California, San Francisco 94143.
Am J Physiol. 1987 Dec;253(6 Pt 1):C802-8. doi: 10.1152/ajpcell.1987.253.6.C802.
The effects of stimulating protein kinase C on Cl- secretion across dog tracheal epithelium were investigated. The phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA), and the synthetic diacylglycerol, 1-oleolyl-2-acetylglycerol (OAG), which stimulate protein kinase C (PKC), both stimulated short-circuit current (Isc) with Kd of 10 nM and 1 microM, respectively. In Cl(-)-free solution, the increases in Isc were virtually abolished, suggesting that these compounds stimulate Cl- secretion, a hypothesis confirmed for TPA by measurement of 36Cl- fluxes. The stimulations of Cl- secretion were not sensitive to indomethacin, nor were cAMP levels elevated during stimulation. In addition to its transient stimulatory effect, TPA at high doses caused the eventual lowering of the base-line Isc and a block of subsequent stimulation by cAMP-mediated agonists. This was probably not the result of toxicity or an effect on adenylate cyclase or on cAMP-dependent protein kinase. Cell extracts from both cultured and native dog tracheal epithelial cells showed strong PKC activities. These results suggest that PKC may play a role in regulating Cl- secretion across dog tracheal epithelium.
研究了刺激蛋白激酶C对犬气管上皮细胞氯离子分泌的影响。佛波酯12 - O - 十四酰佛波醇 - 13 - 乙酸酯（TPA）和刺激蛋白激酶C（PKC）的合成二酰甘油1 - 油酰 - 2 - 乙酰甘油（OAG），均能刺激短路电流（Isc），其解离常数（Kd）分别为10 nM和1 μM。在无氯离子溶液中，Isc的增加几乎完全消失，表明这些化合物刺激氯离子分泌，通过测量36Cl - 通量证实了TPA的这一假设。氯离子分泌的刺激对吲哚美辛不敏感，刺激过程中环磷酸腺苷（cAMP）水平也未升高。除了其短暂的刺激作用外，高剂量的TPA最终导致基线Isc降低，并阻断随后cAMP介导的激动剂的刺激。这可能不是毒性作用的结果，也不是对腺苷酸环化酶或cAMP依赖性蛋白激酶的影响。来自培养的和天然犬气管上皮细胞的细胞提取物均显示出很强的PKC活性。这些结果表明，PKC可能在调节犬气管上皮细胞氯离子分泌中起作用。
