中文摘要：

目的：探讨糖尿病兔心肌缺血早期心肌细胞超微结构和心肌组织中肿瘤坏死因子α（TNF-α）表达水平的变化及其作用机制,为研究糖尿病心肌缺血损伤发生机制提供理论依据.方法：选择42只健康雄性新西兰大白兔,其中26只采用四氧嘧啶耳缘静脉注射方法建立糖尿病模型,将建模成功的22只白兔采用开胸部分结扎冠状动脉左前降支方法建立糖尿病心肌缺血模型.将建模成功的16只糖尿病心肌缺血模型兔分为糖尿病心肌缺血7 d组和28 d组（n=8）,其余16只白兔按照相应时间点分为假手术对照7 d和28 d组（n=8）,只穿线不结扎.透射电镜下观察各组兔心肌细胞超微结构,TUNEL法测定各组兔缺血心肌组织中心肌细胞凋亡指数（AI）,实时荧光定量PCR法测定各组兔缺血心肌组织中TNF-α表达水平.结果：假手术对照组兔心肌细胞核较大,核内染色质分布均匀,肌原纤维排列规则,肌节整齐,肌原纤维间线粒体丰富,结构清晰,而糖尿病心肌缺血组兔早期心肌细胞核不规则,肌原纤维结构松散,部分肌原纤维断裂,心肌细胞间线粒体增生明显.与假手术对照组比较,糖尿病兔心肌缺血7 d和28 d组缺血心肌细胞AI和TNF-α表达水平均明显升高（P〈0.05）,且心肌缺血7 d组高于心肌缺血28 d组（P〈0.05）.结论：糖尿病兔心肌缺血早期发生心肌细胞超微结构破坏,心肌细胞凋亡增加;且TNF-α表达水平的升高参与了糖尿病心肌缺血损伤的发生.

英文摘要：

Objective：To investigate the changes of ultrastructure of myocardial cells and the expression levels of tumor necrosis factor α（TNF-α） in myocardium tissue of the diabetic rabbits during early myocardial ischemia and their mechanisms,and to provide the theoretical basis for studying the pathogenesis of diabetic myocardial ischemia injury.Methods：A total of 42 healthy male New Zealand white rabbits were chosen.The method of intravenous injection of alloxan in ear vein was used to establish the diabetic models in 26 rabbits among 42 rabbits;the method of partial ligation of left anterior descending coronary artery by thoracotomy was used to establish the diabetic myocardial ischemia models in 22 model rabbits with diabetes.A total of 16 （modeling succesfully） were divided into diabetic myocardial ischemia 7 d group and 28 d group;other 16 rabbits were used as sham operation groups at the relevant time points（7 and 28 d）,and there were 8 rabbits in each group.The ultrastructure of myocardial cells was observed by transmission electron microscope;the apoptosis index （AI） of myocardial cells in ischemic myocardium tissue of the rabbits was detected by TUNEL method;the expression levels of TNF-α in ischemic myocardium tissue of the rabbits were detected by real-time RT-PCR method.Results：In sham operation groups,the nuclei of myocardial cells was bigger,the nuclear chromatin was in uniform distribution,the myofibril ordered arrangement,the sarcomere was neat;the mitochondria between myofibril were rich,and their structures were clear.For the rabbits in diabetic myocardial ischemia group,their early-stage cardiocyte nuclei were irregular in shape,myofibrils was loose in structure,the part of myofibril was broken,and the mitochondrial hyperplasia between the myocardial cells was obvious.Compared with sham operation groups,the AI of myocardial cells and the expression levels of TNF-α in the ischemic myocardial cells of the rabbits in diabetic myocardial ischemia 7 d and 28 d groups were significa