实验小猪急性心肌梗死后心肌细胞凋亡机制的动态研究

Myocardial apoptosis mechanism of dynamic analysis after acute myocardial infarction

目的动态观察实验小猪急性心肌梗死(Acute Myocardial Infarction,AMI)后心肌梗死部位的缺血区心肌细胞凋亡及Caspase-3蛋白的表达,探讨AMI后心肌细胞的凋亡机制。方法将8只中华小猪全麻后行冠脉造影及钝缘支(Obtuse Marginal Branch,OM)明胶海绵封堵术,其中1只小猪作为对照组仅行冠脉造影,余7只小猪AMI模型建立成功后,分别于心梗后第1、3、5、7、10、14和28d处死小猪,并取心肌梗死部位的缺血区行TUNEL(TdT-mediated dUTP Nick-End Labeling)法检测心肌细胞凋亡指数(Apoptotic Index,AI)及免疫荧光检测心肌组织中Caspase-3蛋白表达情况,并按caspase-3阳性表达密度进行统计。结果TUNEL法检测心肌AI结果,对照组心肌AI为(2.1±1.0)%,各实验组心肌AI分别是(67.8±4.3)%、(43.6±5.7)%、(39.5±4.2)%、(38.3±7.4)%、(26.7±3.5)%、(19.8±6.2)%和(18.6±5.4)%;对照组caspase-3表达密度为3.6%,各实验组依次是78.8%、58.2%、56.3%、54.5%、49.6%、34.6%和32.1%。通过成功建立小猪AMI模型并观察心肌AI在心梗后第1d达最高峰,依次逐渐下降,在第5~7d下降基本上呈平稳状态,在第14~28d处于低水平状态;免疫荧光caspase-3阳性表达在心梗后第1d达顶峰,后逐渐下降,直至第14~28d呈低水平表达。结论在AMI后心肌梗死周边及缺血区域发现有大量凋亡因子-caspase-3蛋白存在,在心肌受到急性缺血缺氧刺激时,加速诱导心肌细胞凋亡的启动,出现细胞凋亡现象,这与心肌重构、心肌间质纤维化及心肌收缩功能等心脏结构及功能改变密切相关。

Objective To observe myocardial cell apoptosis and Caspase-3 protein expression of myocardial infarction area after acute myocardial infarction （AMI） and explore the mechanisms of myocardial cell apoptosis after AMI.Methods 8 pigs were treated with coronary angiography and obtuse gelatin sponge closure. 1 pig was only treated with coronary angiography as control. The other 7 pigs were executed at 1d, 3d, 5d, 7d, 10d, 14d and 28d. The apoptosis and Caspase-3 protein expression of myocardial infarction area were detected.Results The AI of control and the pig executed at 1d, 3d, 5d, 7d, 10d, 14d and 28d were （2.1±1.0）%, （67.8±4.3）%, （43.6±5.7）%, （39.5±4.2）%, （38.3±7.4）%, （26.7±3.5）%, （19.8±6.2）% and （18.6±5.4）%. The expression density of Caspase-3 of control and the pig executed at 1d, 3d, 5d, 7d, 10d, 14d and 28d were 36%, 788%, 58.2%, 56.3%, 54.5%, 49.6%, 34.6% and 32.1%.Conclusion After AMI, myocardial infarction and ischemia area present a large number of apoptotic factors caspase-3 protein. Acute ischemia during myocardial hypoxia stimulation accelerates the induction of the launch of the myocardial cell apoptosis, apoptosis occurs. The myocardial remodeling, myocardial fibrosis and myocardial systolic function change are closely related to the cardiac structure and function.