尼可地尔预先给药对心肌缺血再灌注兔心肌细胞凋亡的影响

Effects of nicorandil pretreatment on myocardial apoptosis in a rabbit model of myocardial ischemia/ reperfusion

目的观察尼可地尔预先给药对心肌缺血再灌注兔心肌细胞凋亡的影响。方法 雄 性新西兰白兔40只,随机分为5组(n=8),假手术组(Sham组):仅穿线,不结扎;IR组:缺血30 min再 灌注120min;Nic组:缺血前10min静脉注射尼可地尔100μg·kg-1负荷量,随后以10μg·kg-1·min-1的 速率持续静脉输注至缺血前即刻;Nic+5-HD、Nic+Gli组:在缺血前20 min静脉注射五羧基葵酸钠或 格列本脲5 mg·kg-1,其余的处理同Nic组。再灌注120 min时处死兔,计算心肌梗塞面积,通过两种染 色方法检测心肌细胞凋亡情况,观察心肌超微结构改变,并用免疫组织化学方法测定活化的caspase-3 蛋白表达。结果与IR组比较,Nic组心肌梗塞面积减小,早期凋亡细胞数减少,活化的caspase-3蛋 白表达下降(P<0．05),与Sham组比较,Nic组心肌仍有一定损伤,但较IR组明显改善。与Nic组比 较,Nic+5-HD、Nic+Gli组心肌梗塞面积、早期凋亡细胞数、活化的caspase-3蛋白表达增加(P< 0．05)。结论尼可地尔预先给药对缺心肌血再灌注损伤有一定的保护作用,主要通过开放mito-KATPC 及下调活化的caspase-3蛋白的表达。

Objective To investigate the effects of nicorandil （Nic） pretreatment on myocardial apeptosis in a rabbit model of myocardial ischemia/reperfusion （I/R） .Methods Forty healthy male New Zealand white rabbits aged 4 months weighing 2.0-2.5 kg were randomly allocated to one of 5 groups （ n = 8 each） ; group 1 sham operation; group 2 I/R; group 3 Nic; group 4 Nic ＋ 5-hydroxydecanoic acid （5-HD） and group 5 Nic ＋ glibenclamide （Gli） . The animals were anesthetized with IV pentobarbital 30 mg·kg^-1 and tracheotomized and breathing spontaneously. A piece of thread was placed around the circumflex branch of left coronary artery, which was reversibly occluded for 30 min and released for 120 min reperfusion. In group 3, 4 and 5 a loading dose of 100 μg·kg^-1 Nic was given IV 10 min before myocardial ischemia followed by Nic infusion at 10 μg·kg^-1·min^-1 until myocardial ischemia was started. In group 4 and 5 5-HD 5 mg·kg^-1or Gli 5 mg·kg^-1 was given IV 20 min before ischemia. At the end of 120 min reperfusion the animals were killed and the hearts removed. The area of myocardial infarct （AI）, and the ischemic risk zone （AR） were determined by computer morphometry. The early apoptotic myocytes were detected by flow cytometry （Beckman, Coulter Co）. The expression of caspase-3 protein was determined by immuno-histochemistry. The myocardial ultrastructure was examined with transmission electron microscope. Results Compared to group 2 （I/R）, in nicorandil group （group 3） the size of myocardial infarct and the number of early apoptotic cells were significantly reduced, the ultrastructure of myocardium was well-preserved and the expression of activated caspase-3 protein decreased. The protective effect of Nic preconditioning was greatly inhibited by 5-HD and Gli pretreatment. Conclusion Nicorandil pretreatment exerts protective effect against myocardial I/R injury through activation of mito-KATP C and inhibition of activation of caspase-3.