急性缺血再灌注心肌细胞凋亡及凋亡基因与左室局部功能的实验研究

目的 应变率成像观察犬急性缺血再灌注后左心室局部功能，与细胞凋亡及心肌组织中caspase-3 mRNA和蛋白表达的变化。方法 健康杂种犬30只，分对照组（10只），缺血组（10只），再灌注组（10只）。缺血组于第一对角支1cm以下套扎左冠状动脉前降支30min，再灌注组套扎30min后再灌注120min，对照组游离左冠状动脉前降支不结扎。超声心动图左室收缩期应变率测量左室局部收缩功能，TUNEL法检测缺血区心肌细胞凋亡数，RT-PCR法检测caspase-3 mRNA的表达，免疫组化法测caspase-3蛋白的表达。结果 结扎30min后，左室前壁缺血节段收缩期应变率明显降低（P〈0.01）。并出现收缩后压缩（PSC），再灌注120min后缺血节段的应变率有所恢复，但仍低于对照组（P〈0.05）。缺血组缺血区心肌TUNEL阳性细胞数与对照组比较无显著性差异;再灌注组缺血区心肌TUNEL阳性数明显增加（P〈0.05）。缺血组缺血区caspase-3 mRNA与对照组比较表达增高（P〈0.05），再灌注组进一步增高（P〈0.01）。缺血组缺血区心肌细胞caspase-3表达升高，与对照组比差异有显著意义（P〈0.05），再灌注组caspase-3表达进一步增强（P〈0.01）。结论 急性心肌缺血再灌注促凋亡基因capase-3激活，缺血心肌细胞凋亡可能为其早期改变，应变率成像可以评价缺血早期心肌局部收缩功能。

Cell apoptosis, caspase-3 mRNA and protein expression, left ventricular segmental function in acute myocardial ischemia reperfusion: experimental study

Objective To investigate the changes of apoptosis and caspase-3 expression, left ventricular segmental function using strain rate imaging following acute ischemia reperfusion in dogs. Methods Thirty dogs were divided into ischemia (10), reperfusion (10), and control (10) groups. Left anterior descending coronary artery (LAD) were occluded 30 min in ischemia group, dogs in reperfusion group were studied at LAD ligation 30 min, following reperfusion 120 min. Dogs without LAD ligation were used as control group. The left ventricular segmental function were detected by echocardiography using strain rate anlysis software. The percentage of apoptosis in left myocardial dysfunction was detected by terminal deoxynudeotidy transferease-mediated biotinylated deoxyuridine triphosphate nick end labeling (TUNEL). Caspase-3 mRNA and protein expression were analyzed by RT-PCR and immunohistochemistry. Results The peak strain rate (SRpeak) in ischemia group decreased obviously (P<0.01), and postsystolic compression (PSC) was found in ischemia segment. SRpeak increased slightly after reperfusion 120 min, but still decreased than control group. The positive cell of TUNEL detected in ischemia myocardial had no difference between ischemia group and control groups, and increased in reperfusion group (P<0.05). Caspase-3 mRNA and protein expression increased more significantly in ischemia group than that in control group. And significantly increased in reperfusion group (P<0.01). Conclusion Caspase-3 expression and cell apoptosis may be the early changes following acute ischemia reperfusion in dogs, which are related to the left ventricular segmental function.