钙离子拮抗剂对大鼠心肌梗死后心肌细胞凋亡的影响

目的探索钙离子拮抗剂对缺血后心肌细胞凋亡的影响.方法结扎大鼠冠状动脉(冠脉)造成心肌梗死;实验组动物冠脉结扎前和术后3 h分别经口腔内滴注和腹腔注射钙离子拮抗剂Adalat 1 mg/kg和0.4 mg/kg,缺血对照组给安慰剂;正常对照组行假手术不结扎冠脉,给安慰剂.术后6 h测定左室功能,并取心脏标本作原位缺口末端标记法(TUNEL)原位细胞凋亡和Fas、Bcl-2蛋白免疫组织化学(组化)染色,高倍镜下计算细胞凋亡指数.结果实验组和缺血对照组的左室收缩压、左室舒张末压和压力改变速度(dp/dt)无显著差异,3个指标分别为76.7±7.5/8.0±6.1 mm Hg比74.9±11.1/11.6±8.3 mm Hg,P>0.05;(777.3±128.6)mm Hg/s比(761.8±136.4)mm Hg/s,P>0.05;但均低于正常对照组[94.9±7.5/2.8±3.2 mm Hg,P<0.001;(1 131.5±112.8)mm Hg/s,P<0.001];实验组和缺血对照组心肌缺血区TUNEL染色阳性,实验组心肌细胞凋亡指数显著低于缺血对照组(0.201±0.053比0.261±0.045,P<0.05),在缺血周边的心肌区Fas和Bcl-2蛋白免疫组化染色阳性,而正常对照组3种染色均阴性.结论缺血可诱导心肌细胞凋亡及Fas和Bcl-2基因的表达;钙离子拮抗剂具有抑制心肌细胞凋亡的作用.

Effects of Ca2+ antagonist on cardiomyocytic apoptosis after experimental myocardial infarction

OBJECTIVE: To explore the effects of Ca(2+) antagonist on apoptosis of cardiomyocytes after myocardial ischemia. METHODS: The model of myocardial infarction was made by ligating left coronary artery in SD rats. In experimental group, the rats were administrated with Adalat through oral cavity (1 mg/kg) before operation and through peritoneal cavity (0.4 mg/kg 3 hours after operation. In ischemic control group the rats were injected with placebo and in normal control group the rats were treated with sham operation (no ligating left coronary artery) and placebo. The rats were killed 6 hours after operation, with their left ventricular function had been measured. Apoptotic myocardial cells were detected by terminal deoxynucleotidyl transferase mediated dUTP nick end-labeling (TUNEL) method, Fas and Bcl-2 proteins by the ABC immunohistochemistry method. Apoptosis indexes were calculated under high magnification field of microscopy. RESULTS: The systolic pressure, end-diastolic pressure and dp/dt of left ventricle in experiment group were not significant different from those in the ischemic control group, they were 76.7+/-7.5/8.0+/-6.1 mm Hg vs. 74.9+/-11.1/11.6+/-8.3 mm Hg (P>0.05) and (777.3+/-128.6)mm Hg/s vs. (761.8+/-136.4)mm Hg/s (P>0.05) respectively; but those in both the experimental group and the ischemic control group were lower than those in the normal control group, they were 94.9+/-7.5/2.8+/-3.2 mm Hg (P<0.001) and (1131.5+/-112.8)mm Hg/s(P<0.001). There were a lot of positive myocytes with TUNEL stain in the ischemic region of left ventricle in both the experimental and the ischemic control group, apoptosis index in the experimental group was lower than that in the ischemic control group (0.201+/-0.053 vs. 0.261+/-0.045, P<0.05). The positive myocytes of Fas and Bcl-2 protein appeared in the region surrounding ischemic myocytes. There were no positive myocytes with the three types of stain in normal control group. CONCLUSION: Ischemia could induce apoptosis of myocytes and expression of Fas and Bcl-2 gene; Ca(2+) antagonist could protect myocytes from apoptosis.