心肌肥厚大鼠细胞核内蛋白激酶和蛋白磷酸酶的活性

探讨细胞核磷酸化和去磷酸化在心肌肥厚发生中的作用 ,制备腹主动脉缩窄大鼠心肌肥厚模型、差速离心和密度梯度离心提纯心肌细胞核 ,同位素3 2 P掺入法测激酶活性 ,无机磷生成显色法测定蛋白磷酸酶活性。结果发现 ,与对照组比较 ,腹主动脉缩窄组心肌细胞核丝裂素活化蛋白激酶活性增加 82 .0 3 %(P <0 .0 5) ,膜丝裂素活化蛋白激酶活性无显著变化 ,胞浆丝裂素活化蛋白激酶活性下降 53 .69%(P <0 .0 1 ) ;蛋白激酶A活性均无明显变化。细胞核磷酸酶 2A活性增加 44 .95 %(P <0 .0 5) ,膜磷酸酶 2A增加 36 .75 %(P <0 .0 5) ;细胞核磷酸酶 2B活性增加 43 .57%(P <0 .0 5) ,胞浆磷酸酶活性均无显著增加。正常组心肌细胞核丝裂素活化蛋白激酶活性与胞浆无显著差异 ,但腹主动脉缩窄组心肌丝裂素活化蛋白激酶活性为核 >膜 >胞浆 ,蛋白激酶A活性分布无显著差异 ;磷酸酶 2A、2B和 2C活性分布为核 <膜 <胞浆。结果提示 ,压力超负荷时细胞核内蛋白磷酸化和去磷酸化水平增高 ,可能在介导心肌肥厚的发生中起重要作用。

Activities of Protein Kinases and Phosphoprotein Phospharases in Pressure Overload-induced Hypertrophic Rat's Hearts

Aim To observe whether protein phosphorylation and dephosporylation in nuclei play roles in the development of myocardial hypertrophy and distribution of protein kinases and phosphatases in cell fractions were determined. Methods The model of hypertensive rat was established by abdominal aortic constriction. Velocity and isopyknic gradient centrifugation was employed to fractionate rat myocardium to membrane, cytosole and nuclei. Enzymatic methods were employed to determine kinases and phosphatases. Results Compared with control group, the activity of mitogen activated protein kinase (MAPK) increased by 82.03% (P<0.05) in nuclear, changed without significance in membranous fraction, whereas declined by 53.69% (P<0.01) in cytosolic fraction; the activity of protein kinase A (PKA) in different fractions were close to those of control; the activity of PPase 2A increased by 44.95% (P<0.05) and 36.75% (P<0.05) respectively in nuclear and membranous fractions, changed without significance in cytosolic fraction; the activity of PPase 2B increase by 43.57% (P<0.05) in nuclear and changed without significance in membranous and cytosolic fractions; the activity of PPase 2C in different fractions were close to those of control. Conclusions Nuclear MAPK, PPase 2A and PPase 2B might be involved in developing overload induced cardiac hypertrophy.