丙酮酸乙酯对大鼠心肌缺血再灌注细胞凋亡及Bcl-2、Bax蛋白表达的影响

Effects of Ethyl Pyruvate on Myocardial Apoptosis and Expression of Bcl-2 and Bax Protein in Ischemia-reperfusion Rats

目的研究丙酮酸乙酯(EP)对缺血/再灌注(I/R)心肌细胞凋亡及Bcl-2、Bax蛋白表达的影响,探讨其抑制缺血/再灌注心肌细胞凋亡的可能机制。方法应用Langendorff主动脉逆行灌流的体外大鼠缺血/再灌注心脏模型,24只雄性大鼠随机分为3组(每组各8只):对照组,K-H液持续灌流120 min;缺血/再灌注组,平衡灌流30 min,全心停灌30 min,再灌60 min;EP组,实验程序与缺血/再灌注组相同,平衡15 min后和再灌注期间灌流使用含2 mmol/L EP的K-H液。检测心肌丙二醛(MDA)含量,分别以缺口末端标记法(TUNEL法)及免疫组化法检测心肌细胞凋亡指数(AI)及Bcl-2、Bax蛋白表达的变化。结果缺血/再灌注组MDA含量,AI和Bcl-2、Bax蛋白表达水平均明显高于对照组(均P<0.05);与缺血/再灌注组比较,EP组MDA含量,AI与Bax蛋白表达水平均下降,而Bcl-2蛋白表达水平显著增高(均P<0.05)。结论EP可抑制缺血/再灌注后心肌细胞凋亡,此作用可能与其减轻氧化应激、上调Bcl-2和下调Bax蛋白表达水平有关。

Objective To study the effects of ethyl pyruvate on cardiomyocyte apoptosis following ischemia-reperfusion （IR） in vitro and the expression of Bcl-2 and Bax proteins. Methods Isolated rat hearts were perfused in a Langendorff model Twenty-four rats were randomly divided into 3 groups （n = 8 in each group） ： In normal group the rats were perfused for 90 min;In I/R group, after 30 rain stabilization the injury was induced by 30 min global ischemia followed by 30 min reperfusion; In ethyl pyruvate （EP） group the rats were subjected to the same protocol as the I/R group and supplied with 2 mmol/L EP 15 min before ischemia and throughout reperfusion. Myocardial malonaldehyde （MDA） content was measured. Myocardial apoptotic index （AI） was detected by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling （TUNEL） method. The expression of anti-apoptotic protein Bcl-2 and pro-apoptotic protein Bax in cardiac myocytes was detected by immunohistochemistry method. Results Compared with control group, the content of MDA, AI and the expression of Bcl-2, Bax proteins were increased significantly in I/R group;but as compared with control group, the content of MDA, AI and the expression of Bax protein were decreased obviously and the expression of Bcl-2 protein was up-regulated in EP group （P〈0.05）. Conclusion EP can inhibit cardiac myocytes apoptosis probably by alleviating oxidative stress, up-regulating Bcl-2 and down-regulating Bax proteins.