急性心肌梗死大鼠心肌细胞内质网应激和线粒体损伤的研究

Endoplasmic Reticulum Stress and Mitochondrial Damage in Rat Cardiomyocytes after Acute Myocardial Infarction

目的探究急性心肌梗死后心肌细胞内质网应激反应与线粒体损伤的变化趋势,以期进一步了解急性心肌梗死后心肌细胞损伤的具体机制。方法32只SD大鼠建立急性心肌梗死大鼠模型,分别在造模后1 h、2 h、4 h和6 h时各处死8只大鼠,收集心肌组织;对照组(n=8)除未结扎心脏左冠状动脉前降支主干外,余处理均同模型组,处理后6 h时收集心肌组织。通过荧光定量PCR技术检测心肌细胞中激活转录因子6(activating transcription factor 6,ATF6)、免疫球蛋白重链结合蛋白(immunoglobulin heavy chain binding potein,BiP)的mRNA水平和线粒体DNA水平,采用试剂盒检测心肌细胞ATP水平。结果ATF6和BiP的mRNA水平在急性心肌梗死后1 h即出现明显升高,并在2 h及以后维持在较高水平(P<0.05)。心肌细胞ATP水平在急性缺血2 h时出现明显升高,而在4 h及以后出现下降,并低于正常水平(P<0.05)。心肌细胞细胞质中线粒体DNA水平在急性心肌梗死2 h后开始出现明显升高,在4 h和6 h时持续升高(P<0.05)。结论急性心肌梗死后线粒体的损伤可能继发于内质网应激反应。

Objective To study the alterations of endoplasmic reticulum(ER)stress and mitochondrial damage after acute myocardial infarction(AMI).Methods A total of 40 SD rats were used in this study and 32 of them were subjected to AMI by ligation of left anterior descending artery.The rats were sacrificed and the heart tissues were collected after 1 h,2 h,4 h and 6 h of AMI(n=8 per group).The mRNA levels of activating transcription factor 6 alpha(ATF6)and immunoglobulin heavy chain binding potein(BiP),as well as the expression of mitochondrial DNA(mtDNA)in cytoplasm were detected by RT-PCR.The ATP levels in the cardiomyocytes were detected by a commercial ATP assay kit.Results The mRNA levels of ATF6 and BiP were significantly increased after 1 h of AMI,which were maintained at high level from 2 h of AMI to the end of the experiment(P<0.05).The ATP concentrations in the cardiomyocytes were significantly elevated after 1 h of AMI but remarkably decreased after 4 h and 6 h of AMI(P<0.05).The release of mtDNA in cytoplasm was significantly increased after 2 h of AMI,followed by further elevations at 4 h and 6 h after AMI(P<0.05).Conclusion Mitochondrial damage is secondary to ER stress in AMI.