缺血预适应减少心肌缺血损伤机制的研究

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。

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

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.