ACTIVATION OF PROTEIN KINASE C IN VASCULAR SMOOTH MUSCLE

蛋白激酶C是一种磷脂和钙依赖性酶， 被认为是重要的信号转导过程中， 激活磷脂酶C并释放甘油二酯的激素。 最近的研究表明，蛋白激酶C的激活 可能在维持紧张（持续）状态中发挥核心作用 血管平滑肌的收缩。 初步研究 已经证明血管扩张剂，缓激肽和 血管收缩剂，血管紧张素II，都增加细胞内 钙和甘油二酯的形成与 磷脂酶C，但有不同的影响膜结合 血管平滑肌细胞蛋白激酶C活性 （cvsmc）。 这表明蛋白激酶C的调节 活性可能是激素调节 血管反应性 本提案的目标是 进一步探讨造成这些差异的机制 血管紧张素II和缓激肽之间的联系 最可能的解释 这些激素作用于不同的磷脂库， 释放二酰基甘油（或其他因子），其具有不同的 激活蛋白激酶C的能力。 概述的研究 该提案将使用定量酶分析， 内源性磷脂的放射性标记以表征 血管紧张素II和缓激肽对不同磷脂的影响 池. 此外，气相色谱、银化薄层 高压液相色谱法（High Pressure Liquid Chromatography） 用于测定释放的二酰基甘油的分子种类 在暴露于这些激素之后。 最后，一个敏感的 将制备质膜制剂以允许进一步 表征的因素调节的活动， 胞浆和膜结合蛋白激酶C。 的结果 这些研究将提供重要的新信息， 缓激肽的跨膜信号系统， 激素调节蛋白激酶C活性的机制 在血管平滑肌细胞中。 最终，这些研究将 更好地了解激素的细胞基础- 诱导血管收缩和血管舒张，并将提供新的 深入了解血管反应性的生理学， 高血压的病理生理学

Protein kinase C, a phospholipid- and calcium-dependent enzyme, is thought to be important in the signal transduction process of hormones which activate phospholipase C and release diacylglycerol. Recent studies have suggested that activation of protein kinase C may play a central role in maintaining the tonic (sustained) state of contraction seen in vascular smooth muscle. Preliminary studies have demonstrated that the vasodilator, bradykinin and the vasoconstrictor, angiotensin II, both increase intracellular calcium and diacylglycerol formation consistent with activation of phospholipase C, yet have different effects on membrane-bound protein kinase C activity in cultured vascular smooth muscle cells (cvsmc). This suggests that regulation of protein kinase C activity may be a fundamental mechanism whereby hormones modulate vascular reactivity. The goal of the present proposal is to further explore the mechanisms which account for these differences between angiotensin II and bradykinin. The most likely explanation is that these hormones act on different phospholipid pools to release diacylglycerols (or other factors) which possess different capacities to activate protein kinase C. The studies outlined in this proposal will use quantitative enzyme assays as well as radiolabelling of endogenous phospholipids to characterize the effects of angiotensin II and bradykinin on different phospholipid pools. In addition, gas chromatography, argentation thin layer chromatography, and high pressure liquid chromatography will be used to determine the molecular species of diacyglycerol released after exposure to these hormones. Finally, a hormone-sensitive plasma membrane preparation will be prepared to allow further characterization of the factors which regulate the activity of cytosolic and membrane-bound protein kinase C. The results of these studies will provide significant new information on the transmembrane signalling system for bradykinin, and the mechanism(s) by which hormones regulate protein kinase C activity in vascular smooth muscle cells. Ultimately, these studies will provide a better understanding of the cellular basis of hormone- induced vasoconstriction and vasodilitation and will provide new insights into the physiology of vascular reactivity and the pathophysiology of hypertension.