caspase-3活性对老年大鼠心肌缺血再灌注损伤的影响

Effect of the caspase-3 activity on myocardial ischemia reperfusion injury in aged rats

目的 探讨特异的半胱氨酸天冬氨酸蛋白酶 3 (caspase 3 )活性水平对老年大鼠心肌缺血再灌注损伤 (MIRI)的影响。 方法 大鼠在体心肌缺血再灌注模型 ,设青年组和老年组 ;各组分设缺血 3 0min再灌注 1、3、6、12h和 2 4h时相点 ,用荧光分析法检测caspase 3活性 ,缺口末端标记法 (TUNEL)标记凋亡细胞 ,用酶法测定中性粒细胞 (PMNs)浸润数 ,红四唑 (TTC)染色法测梗死范围。 结果 MIRI时 ,青年组和老年组caspase 3活性、心肌细胞凋亡指数 (AI)、PMNs浸润数、心肌梗死范围均随再灌注时间延长而逐渐增加。青年组caspase 3活性和心肌细胞AI于再灌注 12h达到高峰 ,其后维持在较高水平 ;而老年组在再灌注 2 4h仍未下降。所有指标除再灌注 1h外 ,其余各时相点老年组明显较高 ,P <0 0 5～ 0 0 1。 结论 caspase 3参与介导了MIRI时心肌细胞凋亡和PMNs对心肌组织的浸润 ;caspase 3活性水平的增高可能是导致老年大鼠MIRI较青年组严重的重要因素之一。

Objective To investigate the effect of the caspase-3 activity on myocardial ischemia reperfusion injury (MIRI) in aged rats. Methods Wistar rats were divided into young and aged groups. The myocardial samples were observed in Sham, 30 min after ischemia followed by 1,3,6,12 h and 24 h reperfusion. The activity of caspase-3 was determined by fluorescent assay. The apoptosis of cardiomyocytes was determined by TUNEL methods. The content of infiltration of polymorphonuclear neutrophils (PMNs) were measured with MPO enzyme marker and the myocardial infarction area was evaluated by TTC dyeing. Results With the time of reperfusion prolonging the activity of caspase-3,apoptotic index (AI),count of PMN filtration, and myo-cardial infarct size increased in both groups. In young group the activity of caspase-3 and AI achieved their peak respectively at 12 h, and then maintained higher status; but in aged group the activity did not decrease even at 24 h of reperfusion. Additionally, those indices mentioned above were distinctly higher in aged group than those in young group in respective phases except for 1 h of reperfusion ( P <0.05). Conclusions Caspase-3 is involved in induction of myocyte apoptosis and myocardium filtration of PMNs after ischemia-reperfusion injury. Furthermore, the increase of caspase-3 activity may play an important role in induction of more serious MIRI in aged group compared with young group.