缺氧预处理对乳鼠心肌细胞蛋白激酶C活性的影响

EFFECT OF ANOXIC PRECONDITIONING ON PROTEIN KINASE C ACTIVITY IN NEONATAL RAT CARDIOMYOCYTES

在培养的乳鼠心肌细胞缺氧／复氧（A／R）模型上，观察缺氧预处理（APC）的细胞保护作用及其对细胞蛋白激酶C（PKC）活性和蛋白磷酸化的影响。结果表明，APC可减轻心肌细胞的H／R损伤：提高细胞存活率（P＜0．01），减少细胞脂质过氧化产物（MDA）生成（P＜0．01）及细胞内乳酸脱氢酶（LDH）和蛋白质的漏出（P＜0．01）。模拟APC的短暂缺氧（TA）显著激活PKC（125．0±11．2vs对照组52．1±8．4pmolPi／106cells，P＜0．01），使心肌细胞内分子量为66kD和31kD的蛋白条带32P掺入增加；PKC抑制剂H7完全消除APC对心肌细胞的保护作用，并抑制了短暂缺氧引起的PKC激活及蛋白磷酸化反应。磷酸酶抑制剂OA模拟，而激动剂BDM完全消除APC的保护作用；提示PKC介导了APC对心肌细胞的保护，其机理涉及PKC对其底物蛋白的磷酸化。

In a model of anoxia/reoxygenation (A/R) of cultured rat cardiomyocytes, protection of cellular damage, activation of protein kinase C (PKC) and PKC-mediated protein phosphorylation by anoxic preconditioning (APC) can be demonstrated as shown bythe increase of cell viability, attenuation of formation of lipid peroxides (MDA) andlowering of the leakage of lactate dehydrogenase (LDH) and protein from cells. The results also show that transient anoxia mimicked the outcomes of activation of PKC asshown by increased incorporation of 32P, especially in the 66 kD and 31 kD proteinfractions, Preincubation of cardiomyocytes with H7 (an inhibitor of PKC) completelyabolished these protective effects of transient anoxia. Protein phosphatase inhibitor OAmimicked the protective effects of A/R, while protein phosphatase activator BDM induced a complete abolishment. In short, we conclude that the protective effect of APCis medicated by activation of PKC.