Effect of preconditioning with penehyclidine hydrochloride on mitochondria-dependent pathway of apoptosis during myocardial ischemia-reperfusion in rats

Objective To evaluate the effect of preconditioning with penehyclidine hydrochloride(PHC)on mitochondria-dependent pathway of apoptosis during myocardial ischemia-reperfusion(I/R)in rats. Methods Twenty-four healthy adult male Wistar rats were allocated into 3 groups(n=8 each) using a random number table: sham operation group(group S), I/R group and PHC preconditioning group(group P). Myocardial I/R was produced by occlusion of left anterior descending branch of coronary artery for 30 min followed by 3 h reperfusion.PHC 1.0 mg/kg was injected via the tail vein at 30 min before occlusion in group P. The rats were sacrificed at the end of reperfusion, hearts were removed and left ventricular specimens were obtained for determination of apoptosis in cardiomyocytes(by TUNEL), and apoptosis index(AI)was calculated.Mitochondria and cytoplasm were isolated for detection of mitochondrial membrane potential(MMP, by JC-1 method)and expression of Bcl-2, cytochrome c(Cyt c)in mitochondria and cytoplasm and activated caspase-3 in myocardial tissues(by Western blot). Results Compared with group S, AI was significantly increased, the expression of Bcl-2 and mitochondrial Cyt c was down-regulated, MMP was decreased, and the expression of Cyt c in cytoplasm and activated caspase-3 was up-regulated in I/R and P groups(P<0.05). Compared with group I/R, AI was significantly decreased, the expression of Bcl-2 and mitochondrial Cyt c was up-regulated, MMP was increased, and the expression of Cyt c in cytoplasm and activated caspase-3 was down-regulated in group P(P<0.05). Conclusion The mechanism by which PHC preconditioning attenuates myocardial I/R injury is related to inhibiting mitochondria-dependent pathway of apoptosis in rats. Key words: Cholinergic antagonists; Apoptosis; Myocardial reperfusion injury