替米沙坦对缺血再灌注兔心肌细胞凋亡的影响

The Effect of Telmisartan on Rabbit Apoptotic Cardiomyocytes Underwent Ischemia Reperfusion Injury

目的探讨替米沙坦对缺血再灌注兔心肌细胞凋亡的影响。方法 48只雄性新西兰大白兔随机分为6组:假手术组、缺血再灌注模型组、GW9662组、替米沙坦组、替米沙坦+GW9662组、坎地沙坦组,每组8只。灌胃给药2周,假手术组左前降支近端穿线但不结扎,其余5组予60 min缺血,360 min再灌注。采用放射免疫法检测心肌血管紧张素Ⅱ含量,双波长荧光分光光度法测定心肌细胞内游离钙浓度,免疫印迹法测定过氧化体增殖物激活型受体γ蛋白的表达,透射电镜和末端标记法检测心肌细胞凋亡。结果缺血再灌注模型组、GW9662组、替米沙坦组、替米沙坦+GW9662组及坎地沙坦组心肌血管紧张素Ⅱ含量均较假手术组明显增高(P<0.01)。替米沙坦组过氧化体增殖物激活型受体γ蛋白的表达明显高于其余各组(P<0.01)。电镜显示,替米沙坦、替米沙坦+GW9662及坎地沙坦抑制心肌缺血再灌注诱导的心肌细胞凋亡的特征性形态学改变如核染色质浓缩边集,出现凋亡小体等。与缺血再灌注模型组比较,替米沙坦组、替米沙坦+GW9662组和坎地沙坦组心肌细胞游离钙浓度、凋亡指数均明显降低(P<0.01);替米沙坦组凋亡指数显著低于替米沙坦+GW9662组和坎地沙坦组(P<0.01)。结论替米沙坦通过阻断血管紧张素Ⅱ1型受体降低细胞内钙浓度,并通过上调过氧化体增殖物激活型受体γ的表达,抑制兔缺血再灌注心肌细胞凋亡而发挥心肌保护效应。

Aim To investigate the effect of telmisartan on rabbit apoptotic cardiomyocytes underwent ischemia/reperfusion（I/R） injury. Methods 48 Healthy male New Zealand white rabbits were randomly divided into six groups（n=8）： sham operation group,I/R model group,GW9662 group,telmisartan group,telmisartan＋GW9662 group,candesartan group.After intragastric administration for 2 weeks,the left anterior descending（LAD） coronary artery was occluded for 60 minutes followed by 360 minutes reperfusion to induce ischemia/reperfuion injury.The concentration of angiotensinⅡ in myocardium was analyzed by radioimmunoassay and the intracellular free calcium concentration was measured by dual wavelength fluorophotometry.Then,protein expression of peroxisome proliferator activated receptor-γ（PPARγ） was detected by Western blot.In addition,apoptosis was detected by transmission electron microscope and by TUNEL staining. Results Compared with sham operation group,the concentration of angiotensinⅡin myocardium was significantly increased in I/R model group,GW9662 group,telmisartan group,telmisartan＋GW9662 group,and candesartan group（P0.01）.And,the expression of PPARγ was higher in telmisartan group than that in other groups（P0.01）.Interestingly,telmisartan,telmisartan＋GW9662 and candesartan inhibited the morphological chan ges of apoptotic cardiomyocytes,which was induced by myocardial ischemia/reperfusion,by condensing chromatin clumps against the nuclear envelope and presentation of apoptotic body.When compared with I/R model group,the intracellular free calcium concentration and apoptosis index were significantly reduced in telmisartan group,telmisartan＋GW9662 group and candesartan group（P0.01）.Among them,apoptosis index was lowest in telmisartan group（P0.01）. Conclusion Telmisartan could reduce myocardial apoptosis by blocking the angiotensinⅡreceptor and up-regulating the expression of PPARγ in the rabbit I/R model.