心肌凋亡在兔心肌梗死过程中的作用

摘要

Objective To study the changes of the myocardial cell apoptosis in myocardial infarction of rabbits. Methods The model of rabbit with myocardial infarction was established.HE staining,TUNEL staining, immunohistro-chemistry staining, ultrathin section for electron microscope and DNA electronic gel phorensis were performed in samples of ischemia or infarction in different times.The position of apoptotic myocytes in different phases of ischemia were observed by light microscope and electronic microscope. Results After 30 minutes to 4 weeks ischemia.there were a few TUNEL positive nucleus of myocytes in the margin area of myocardial infarction;HE staining-found typical expressions of apoptosis,such as chromosome conglomeration,chromosome gathered at the edge or chromosome aggregation,dark-stained nucleus,cell shrinkage,were obvious in 4-8 hours.A lot of positive nucleus of myocytes stained by TUNEL were found in the early stages of myocardial ischemia in myocardial infarction.gradually ascended and then became hardly visible from 8 hours to 3 days.Nucleus swelling,karyorrhexis and karyolysis were found in the area of myocardial infarction.then cells were broken.DNA agarose electrophoresis found DNA fragment of most myocytes in 30 minutes of ischemia,just a few cardiocytes decomposed to the big segments.At 4hours of ischemia the most cardiocytes decomposed to big segments,and there were a blurry"ladder"in DNA strand breaks from 8 hours to 1 day.It showed that apoptotic cardiocytes existed in the margin area of myocadial infarction. Conclusions There are cardiocytes apoptosis in the margin area of infarction from 30 minutes to 4 weeks after myocardial ischemia.Maybe it relates to the reperfusion caused by collateralization establishment or infiltration from circumference.%目的 探讨心肌细胞凋亡在心肌梗死过程中的作用.方法 通过制备兔心肌缺血、梗死模型,对不同时间缺血或梗死心肌标本进行HE染色、原位末端标记(TUNEL)法染色、免疫组织化学染色、超薄切片电镜及DNA凝胶电泳等方法检查,观察缺血不同时相凋亡心肌细胞出现的部位.结果 缺血30 min至4周,在心肌梗死边缘区均有少量散在TUNEL阳性心肌细胞,HE染色表现为细胞核染色质凝聚或边集,胞核染色深,细胞有皱缩,呈典型的凋亡形态改变,以4～8 h明显.梗死区心肌细胞在缺血早期,细胞核TUNEL染色均呈阳性,8 h～3 d细胞核TUNEL阳性染色逐渐减少,至背景染色;HE染色,梗死区心肌细胞均表现核固缩、肿胀及破裂,最终导致细胞破裂.DNA凝胶电泳可见缺血30 min大部分心肌细胞DNA无降解,仅有少量心肌细胞DNA降解成较大的片段;4 h梗死区大部分心肌细胞DNA降解成较大的片段,与30 min的少量大片段一致,8 h与1 d,在涂片样坏死DNA带中有较淡的梯形带,表明心肌梗死边缘区有凋亡心肌细胞.结论 兔心肌缺血30 min至4周,凋亡心肌细胞均散在出现于心肌梗死边缘区,可能与周围侧支循环开放,引起再灌注或周围向梗死区的渗透有关.