杨梅苷对大鼠离体心脏缺血再灌注损伤的保护作用

Protective effects of myricitrin on ischemic/reperfusion injury in isolated rat hearts

目的研究杨梅苷对大鼠离体心脏缺血再灌注损伤的保护作用及其机制。方法 60只SD大鼠随机分为6组:正常对照组、模型组、阳性给药组(维拉帕米100μg/L)和杨梅苷低中高剂量组(2.5,5,10 mg/L),每组10只。釆用Langendorff离体心脏灌流技术,停灌30 min,再灌45 min,造成心肌缺血再灌注损伤模型。记录杨梅苷对心脏血流动力学指标的影响,测定冠脉流出液中心肌三酶LDH、CK、AST的水平,心肌组织中抗氧化酶SOD、CAT的活性及脂质过氧化物MDA的含量。HE染色观察心肌组织病理学变化。Western blot检测凋亡相关蛋白的表达。结果杨梅苷低中高剂量组大鼠心脏血流动力学指标显著改善,冠脉流出液中LDH、CK、AST的释放减少,心肌组织中SOD、CAT的活性增加且MDA的产生减少,不同程度地减轻缺血再灌注造成的心肌损伤。Western blot结果表明杨梅苷能上调Bcl-2的表达,下调Bax和Caspase-3、Caspase-9的表达,同时抑制ERK的磷酸化。结论杨梅苷对心肌缺血再灌注损伤具有保护作用,可以改善心肌收缩功能、增强抗氧化能力、抑制细胞凋亡等,其机制可能是通过抑制ERK信号转导通路缓解缺血再灌注引起的心肌细胞凋亡。

Objective To investigate the protective effect of myricitrin on myocardial ischemia/reperfusion injury in isolated rat hearts and its underlying mechanism. Methods Sixty SD rats were randomly divided into： （ 1 ） control group ; （2） model group ; （3） positive administration group （ verapamil of 100 μg/L） ; （4） three dose groups with varying amount of myricitrin （2.5, 5, 10 mg/L）. Each group included ten rats. The myocardial ischemia/reperfusion injury model was constructed using the Langendorff method. The isolated working hearts were ischemia for 30 min followed by reperfusion for 45 rain after in equilibrium for 15 min. During the process, we determined myocardial hemodynamie parameters,myocardial enzyme indicators （lactate dehydrogenase （LDH）, creatine kinase （CK） and aspartate aminotransferase （AST）） and antioxidative parameters （superoxide dismutase （SOD）, catalase （CAT） and malondialdehyde （MDA））. Furthermore, we performed histopathological examination of left ventricles and detected the expression of apoptosis related proteins （e. g. , Bcl-2, Bax, Caspase-3 and Caspase-9） by western blot. Results Compared with the model group, myricitrin could significantly improve cardiac constriction and relaxation function, decrease the levels of LDH, CK and AST in perfusate, enhance the activities of SOD and CAT, and decrease the content of MDA in myocardial tissue. The cardiac protective effect of myricitrin was further confirmed by histopathological examination. Apparently, myricitrin pretreatment restrained myocardial apoptosis as evidenced by increasing the level of Bcl-2 expression, decreasing the levels of Bax, Caspase-3 and Caspase-9 expression, and inhibiting the phosphorylation of ERK. Conclusions Myricitrin had a protective effect on myocardial ischemia/reperfusion injury. It showed ability of improving myocardial contractile function, increasing anti-oxidation ability and inhibiting apoptosis. The possible mechanism of cardiac protection of myricitrin was that the agent attenuated myocardial cell apoptosis induced by ischemia reperfusion via inhibiting ERK signaling pathway.