Insulin improves cardiomyocyte contractile function through enhancement of SERCA2a activity in simulated ischemia/reperfusion  

作　　者：Jie YU Hai-feng ZHANG Feng WU Qiu-xia LI Heng MA Wen-yi GUO Hai-chang WANG Feng GAO 

机构地区：[1]Department of Physiology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China [2]Department of Cardiology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China [3]Institute of Molecular Medicine, Peking University, Beijing 100871, China

出　　处：《Acta Pharmacologica Sinica》2006年第7期919-926,共8页中国药理学报（英文版）

基　　金：Project supported in part by the National Natural Science Foundation of China(№30370525,30471923,30570667,30500577).

摘　　要：Aim： Insulin exerts anti-apoptotic effects in both cardiomyocytes and coronary endothelial cells following ischemia/reperfusion （I/R） via the Akt-endothelial nitric oxide synthase survival signal pathway. This important insulin signaling might further contribute to the improvement of cardiac function after reperfusion. In this study, we tested the hypothesis that sarcoplasmic reticulum calcium-ATPase （SERCA2a） is involved in the insulin-induced improvement of cardiac contractile function following I/R. Methods： Ventricular myocytes were enzymatically isolated from adult SD rats. Simulated I/R was induced by perfusing cells with chemical anoxic solution for 15 min followed by reperfusion with Tyrode＇s solution with or without insulin for 30 min. Myocyte shortening and intracellular calcium transients were assessed and underlying mechanisms were investigated. Results： Reperfusion with insulin （10^-7 mol/L） significantly improved the recovery of contractile function （n= 15-20 myocytes from 6-8 hearts, P〈0.05）, and increased calcium transients, as evidenced by the increased calcium （Ca^2＋） fluorescence ratio, shortened time to peak Ca^2＋ and time to 50% diastolic Ca^2＋, compared with those in cells reperfused with vehicle （P〈0.05）. In addition, Akt phosphorylation and SERCA2a activity were both increased in insulin-treated I/R cardiomyocytes, which were markedly inhibited by pretreatment of cells with a specific Akt inhibitor. Moreover, inhibition of Akt activity abolished insulin-induced positive contractile and calcium transients responses in I/R cardiomyocytes. Conclusion： These data demonstrated for the first time that insulin improves the recovery of contractile function in simulated I/R cardiomyocytes in an Akt-dependent and SERCA2a- mediated fashion.Aim： Insulin exerts anti-apoptotic effects in both cardiomyocytes and coronary endothelial cells following ischemia/reperfusion （I/R） via the Akt-endothelial nitric oxide synthase survival signal pathway. This important insulin signaling might further contribute to the improvement of cardiac function after reperfusion. In this study, we tested the hypothesis that sarcoplasmic reticulum calcium-ATPase （SERCA2a） is involved in the insulin-induced improvement of cardiac contractile function following I/R. Methods： Ventricular myocytes were enzymatically isolated from adult SD rats. Simulated I/R was induced by perfusing cells with chemical anoxic solution for 15 min followed by reperfusion with Tyrode＇s solution with or without insulin for 30 min. Myocyte shortening and intracellular calcium transients were assessed and underlying mechanisms were investigated. Results： Reperfusion with insulin （10^-7 mol/L） significantly improved the recovery of contractile function （n= 15-20 myocytes from 6-8 hearts, P〈0.05）, and increased calcium transients, as evidenced by the increased calcium （Ca^2＋） fluorescence ratio, shortened time to peak Ca^2＋ and time to 50% diastolic Ca^2＋, compared with those in cells reperfused with vehicle （P〈0.05）. In addition, Akt phosphorylation and SERCA2a activity were both increased in insulin-treated I/R cardiomyocytes, which were markedly inhibited by pretreatment of cells with a specific Akt inhibitor. Moreover, inhibition of Akt activity abolished insulin-induced positive contractile and calcium transients responses in I/R cardiomyocytes. Conclusion： These data demonstrated for the first time that insulin improves the recovery of contractile function in simulated I/R cardiomyocytes in an Akt-dependent and SERCA2a- mediated fashion.

关 键 词：INSULIN ISCHEMIA/REPERFUSION CARDIOMYOCYTE CONTRACTION calcium transients SERCA2A Akt 

分 类 号：R36[医药卫生—病理学]