依那普利对心力衰竭大鼠心肌细胞凋亡及凋亡基因bcl-2、Bax的影响

Experimental study on the effect of apoptosis and bcl-2 , Bax expression in failing myocardium with enalapril in rats

目的:探讨血管紧张素转化酶抑制剂(ACEI)———依那普利对慢性压力负荷性心力衰竭大鼠心肌重构、心肌细胞凋亡、凋亡基因Bcl 2、Bax在心肌细胞中表达的影响,为心力衰竭的发病机制及治疗提供实验依据。方法:结扎大鼠的腹主动脉,复制慢性压力负荷性心力衰竭模型,32只大鼠随机分为心力衰竭组 12 只、依那普利治疗组(治疗组)12只、对照组8只。手术后6周,充血性心力衰竭模型形成。治疗组给予依那普利10 mg·kg-1·d-1灌胃,心力衰竭组和对照组给予同量0.85%氯化钠溶液灌胃。在 3 个月末测量血流动力学指标后,将大鼠处死,取出心脏。用原位脱氧核糖核酸酶末端标记法(TUNEL)检测细胞凋亡;免疫组化法和免疫印迹法测 bcl 2、Bax表达。结果:心力衰竭组与对照组相比,心功能明显减退(P < 0.01);心肌细胞凋亡明显增加(P <0.01);在心肌细胞中bcl 2 表达减低,Bax表达增加。依那普利治疗后能改善心室重构(P<0.05),减少心肌细胞凋亡(P< 0.01),增加bcl 2、减少Bax在心肌细胞中的表达(P<0.05)。结论:在心力衰竭时血管紧张素Ⅱ生成增多,减低bcl 2的表达,增加Bax的表达,从而降低 bcl 2/Bax比率;依那普利可能通过血管紧张素Ⅱ的介导作用,增加bcl 2、减低Bax在心肌细胞中的表达,减轻心肌细胞凋亡。

Objective:To examine the impact of enalapril(ACE inhibitor, ACEI)on myocardial remodeling, apoptosis, pro-apoptotic Bax and anti-apoptotic bcl-2 protein expression in chronic heart failure (CHF) in rats. Method:The rat model of chronic pressure overload HF was induced by transverse abdominal aortic constriction. 32 rats were randomized to 6 weeks of therapy with enalapril (Ena, 10 mg daily, n= 12) or no therapy (CHF, n= 12) or to sham operation without constriction at all (control, n= 8). The CHF rat model was established by transverse abdominal aortic constriction for 6 weeks.After 3 months of study, these rats were killed after measuring haemodynamic parameters and then, hearts removed. The left and right ventricles were dissected and weighed separately. The part of LV free wall was stored for study.The left part was snapped and frozen. Presence of nuclear DNA fragmentation (nDNAf), was assessed by TUNEL method. The expression of Bax, bcl-2 genes were determined by Western blot and immunohistochemistry. Result:In CHF rats, there was significant (P< 0.01) systolic dysfunction. Myocardial apoptosis was significantly increased (P < 0.01). Bax were significantly elevated in heart failure rats. The expression of Bcl-2 was significantly reduced and the bcl-2 to Bax ratio reduced. Immunohisto chemistry confirmed that increased Bax staining in failing myocardium, with reduced Bcl2. Enalapril treatment resulted in: ① improved LV remodeling (P < 0.05),②reduced myocardial apoptosis (P< 0.01), and ③selective reduction in myocardial bcl-2 expression (P < 0.05) with increased Bax expression. Conclusion:These data suggest that adrenergic activation, such as occurs in chronic pressure overload HF, increases cardiomyocyte-specific apoptosis and Bax expression and reduced bcl-2 and the bcl-2 to Bax ratio. ACE inhibitor in HF reduces myocardial apoptosis; prevented the changes of bcl-2 and Bax, may be one mechanism contributing to this effect.