缺血预适应减少心肌缺血损伤机制的研究

Study on the mechanism of action of ischemic preconditioning in protecting myocardium against ischemic injury

目的 通过对心肌缺血预适应的动物模型观察 ,探讨细胞凋亡在其中的作用 ,以及p5 3,bcl 2 ,Bax基因对其发生进行的调控。方法 采用TUNEL标记技术研究心肌缺血预适应心肌细胞中细胞凋亡现象 ,并采用免疫组化染色技术及原位分子杂交技术研究p5 3,bcl 2及Bax基因的蛋白及mRNA的表达。结果 缺血预适应组 (P)及非缺血预适应组 (NP)非缺血区均未见凋亡细胞 ,但在P组缺血区可见散在的凋亡细胞 ,而在NP组缺血区则多见。P组p5 3蛋白表达显著低于NP组 ,bcl 2蛋白表达在P组显著高于NP组 ,Bax蛋白表达在P组显著低于NP组 ,并且bcl 2 /Bax的比值P组与NP组相比显著升高。P组p5 3基因mRNA表达显著低于NP组 ,bcl 2基因mRNA表达在P组显著高于NP组。结论 心肌缺血预适应对心肌的保护可通过抑制细胞凋亡来实现 ,并且通过bcl 2表达增加 ,p5 3、Bax表达减少对其进行调控。

Objective To investigate the apoptosis and the expression of genes p53,bcl 2 and Bax in myocytes treated by ischemic preconditioning in rabbits.Methods The rabbit model was established by acute ischemia reperfusion of myocardium.Ischemic preconditioning model (P,n=10) was produced with occlusion of left anterior descending branch for 5 min followed by 10 minute reperfusion before the 60 minute occlusion and 3 hour reperfusion.Control rabbits(NP,n=10) were subjected to only 60 minute occlusion and 3 hour reperfusion.TUNEL technique was used to observe apoptosis in myocytes,immunohistochemical technique was used to study expression of p53、bcl 2 and Bax proteins in myocytes,and molecular hybridization technique was used to study expression of p53、bcl 2 in myocytes.Results There was no any apoptosis in non ischemic part in either group.There were more myocytes undergoing apoptosis in ischemic parts in NP group than in P group.Myocytes with positive p53 immunoreactivity and myocytes with positive Bax immunoreactivity were decreased in P group as compared with NP group,while myocytes with positive bcl 2 immunoreactivity and the ratio of bcl 2/Bax were enhanced in P group as compared with NP group.Expression of p53 mRNA was inhibited and expression of bcl 2 mRNA was enhanced in P group.Conclusions Apoptosis was involved in the protective effect of ischemic preconditioning in rabbit.p53 and Bax expression were inhibited and bcl 2 expression was enhanced in the preconditioned animals,indicating that these genes may play important role in the regulation of the apoptosis.