环磷酸腺苷对大鼠心肌缺血/再灌注细胞凋亡的影响

目的：通过观察外源性环磷酸腺苷（cAMP）对缺血／再灌注心肌梗死面积、心肌结构和细胞凋亡参数的影响，探讨cAMP抗心肌缺血／再灌注损伤的作用机制。方法：SD大鼠心脏左冠状动脉前降支缺血／再灌注动物模型，缺血30min，再灌注2h。40只SD大鼠随机分成三组：对照组（I组，n＝8），I／R组，（Ⅱ组，n=6)，cAMP治疗组（Ⅲ组，n=16）在缺血前5min静脉注射cAMP(1mg/kg) I/R组。按TCC法染色用图象分析系统计算梗死面积，原位末端TUNEL法检测细胞凋亡指数，免疫组化SP法测定Fas、Bcl-2的含量,在电镜下观察心肌细胞的超微结构。结果：与Ⅱ组比较，Ⅲ组的梗死面积明显缩小（P＜0．05），凋亡指数和Fas含量明显减少（P＜0．01）；B cl-2含量明显增多（P＜0．01）。结论:cAMP具有抗心肌缺血／ 再灌注损伤的作用，其作用机制可能是通过调节Fas和Bcl-2介导的心肌 缺血／再灌注细胞凋亡而实现。

Effect of cAMP on myocardial apoptosis induced by ischemia/ reperfusion injury in rat

ve To investigate the effect of intravenous cAMP on the myocardial infarct size, the ultrastructure of myocardium and myocardial cell apoptosis and the possible mechanism of myocardial protection affected by cAMP against ischemia /reperfusion (I/R) injury. Methods Forty SD rats of either sex weighing 250-280g were anesthetized with abdominal sodium pentobarbital 4.5mg/100g, tracheotomized and mechanically ventilated (VT = 2ml/100g, RR = 60bpm) . Myocardial I/R was produced by tying and untying of left anterior descending coronary artery. Ischemia lasted 30 min and reperfusion 2h. Rats were randomly divided into 3 groups: control group (n = 8) in which left anterior descending coronary artery was exposed and a piece of silk thread was placed around the artery but not tied; I/R group (n = 16) in which normal saline 1ml was injected into sublingual vein before I/R; cAMP group (n = 16) received intravenous cAMP 1mg/kg 5min before I/R. The animals were then sacrificed and heart was harvested for determination of myocardial infarct size (by TTC) and ultrastructure examination (electron microscope) . Apoptosis was identified by TUNEL and apoptosis index (AI) was obtained. The expression of Fas, Bcl-2 protein was measured by immunohistochemical technique. Results The infarct size was smaller in cAMP group than that in I/R group . Myocardial apoptosis and necrosis were quite obvious in I/R group whereas in cAMP group the ultrastructure of myocardium was fairly normal. The AI in I/R group was significantly higher than that in cAMP group (P<0.01). The average OD value of Fas protein was significantly lower in cAMP group than that in I/R group. The average OD value of Bcl-2 protein in cAMP group increased significantly as compared with that in I/R group (P<0.01) but was not significantly different from that in control group (P> 0.05 ) . Conclusions cAMP can protect myocardium from I/R injury by modulating the expression of Fas and Bcl-2 protein and inhibit apoptosis following myocardial I/R.