大鼠急性心肌缺血再灌注损伤诱导细胞凋亡的实验研究

目的:观察心肌缺血再灌注(IR)损伤与心肌细胞凋亡关系及凋亡调控基因Bcl-2、Bax表达情况。方法:选用健康雄性SD大鼠29只,随机分为:假手术组(n=8),缺血组(n=12),缺血再灌注组(n=9),分别取上述大鼠心肌组织。(1)观察心肌组织及线粒体的形态结构,并进行体视学分析。(2)采用缺口末端标记法(TUNEL)原位检测凋亡细胞。(3)用免疫组化SP法检测心肌细胞Bcl-2、Bax表达。结果:(1)假手术组心肌纤维排列整齐,细胞间质血管未见明显异常,细胞核膜完整,缺血组及缺血再灌注组可见心肌嗜酸性变、空泡变性、心肌纤维紊乱及收缩带形成,心肌纤维间出血及灶性心肌坏死。心肌细胞线粒体体视学分析,与假手术组比较,心肌缺血组形状因子显著降低(P<0.05),面密度显著增加(P<0.05),缺血再灌注组形状因子显著降低(P<0.01),面密度及周密度均显著增加(均P<0.05)。(2)与假手术组比较,缺血组细胞凋亡率明显升高(P<0.001),缺血再灌注组细胞凋亡率明显升高(P<0.001)。缺血再灌注组与缺血组比较细胞凋亡率明显升高(P<0.05)。(3)与假手术组比较,缺血再灌注组凋亡调控基因Bcl-2、Bax表达明显升高(P<0.01,P<0.001)。缺血再灌注组与缺血组比较凋亡调控基因Bcl-2、Bax表达明显升高(均P<0.01)。结论:心肌缺血及再灌注在导致细胞形态、线粒体超微结构改变的同时,诱导心肌细胞的凋亡,Bcl-2、Bax蛋白表达在心肌细胞凋亡的发生中起重要作用,细胞凋亡加重了缺血再灌注损伤。

Study of Apoptosis in Experimental Ischemia-Reperfusion Injury In Rat Myoeardium

Objective：To study the mechanism of myocyte apoptosis during myocardial ischemic reperfusion （MIR）in rats, we evaluated the relationship between Bcl-2 and Bax and myocyte apoptosis in MIR. Method： This study established the model of myocardial ischemia/reperfusion injury. In this model, rats were divided into three groups, control group and myocardial ischemia for 30 min and ischemia for 30 min followed by reperfusion for 10 min group. The ultrastructure of myocardial cell was observed by electronic microscope. Myocyte apoptosis in ischemia group and ischemic reperfusion group was studied by TdT-mediated dUTP nick end labeling （TUNEL）. Bcl-2 and Bax was studied by immunohistochemical staining. Result： Comparing with model group, the mitochondria swelled, some vacuoles emerged, the density of electron in the matrix were decreased. The cristallia aligned chaotically, even shortened or vanished. The form facter （FF）were obviously decreased （P 〈 0.05） in ischemia group and ischemia/ reperusion group, the surface density （ Sv ） and the perimeter density were increased, the percentage of apoptosis myocytes were increased, the expression of Bcl-2 and Bax were increased. Conclusion： Myocardium structure and metabolism and the uhrastructure of mitochondria were changed by MIR injury in rats, then myocyte apoptosis and the expression of Bcl-2 and Bax were induced, Bcl-2 and Bax may be important regulative genes in process of apoptosis.