Objective To investigate the mechanism underlying sufentanil postconditioning-induced reduction of myocardial ischemia-reperfusion (I/R) injury in rats through evaluating the relationship between phosphatidylinositol 3-kinase/serine-threonine kinase (PI3K/Akt) signaling pathway and mitochondrial permeability transition pore (mPTP).Methods Forty-eight pathogen-free healthy male SpragueDawley rats,aged 3 months,weighing 250-300 g,were divided into 4 groups (n=12 each) using a random number table:sham operation group (group S),group I/R,sufentanil postconditioning group (group SP) and snfentanil postconditioning plus PI3K inhibitor wortmannin group (group SP +W).The rats were anesthetized with 20％ urethane 5 ml/kg.Myocardial I/R was induced by ligation of the anterior descending branch of left coronary artery for 30 min,followed by 120 min reperfusion.Sufentanil 1.0 μg/kg was injected via the sublingual vein at 5 min before reperfusion in SP and SP+W groups.Wortmannin 15 pμg/kg was injected via the sublingual vein at 5 min before reperfusion,and then sufentanil 1.0 μg/kg was given in group SP+W.Blood samples were taken from the abdominal aorta at the end of reperfusion for detection of serum cardiac troponin I (cTnI) and creatine kinase-MB (CK-MB) concentrations.The rats were then sacrificed and hearts were removed for determination of cell apoptosis (by TUNEL),nicotinamide adenine dinueleotide (NAD+) content (by speetrophotometry),and expression of phosphorylated Akt (p-Akt) in myocardial tissues (by Western blot).Apoptosis index (AI) was calculated.The myocardial mitochondria and cytoplasm were isolated for detection of the expression of cytochrome c (Cyt c) and apoptosis-inducing factor (AIF) using Western blot.Results Compared with group S,the serum cTnI and CK-MB concentrations and AI were significantly increased,the content of NAD+ was decreased,the expression of p-Akt was up-regulated,the expression of Cyt e and AIF in mitochondria was down-regulated,and the expression of Cyt c and AIF in cytoplasm was up-regulated in I/R,SP and SP+W groups (P＜0.05).Compared with group I/R,the serum cTnI and CK-MB concentrations and AI were significantly decreased,the content of NAD+ was increased,the expression of p-Akt was up-regulated,the expression of Cyt c and AIF in mitochondria was up-regulated,and the expression of Cyt c and AIF in cytoplasm was down-regulated in group SP (P＜0.05).Compared with group SP,the serum cTnI and CK-MB concentrations and AI were significantly increased,the content of NAD+ was decreased,the expression of p-Akt was down-regulated,the expression of Cyt c and AIF in mitochondria was down-regulated,and the expression of Cyt c and AIF in cytoplasm was up-regulated in group SP+W (P＜0.05).Conclusion Sufentanil postconditioning can activate PI3K/Akt signaling pathway,inhibit mPTP opening,mitigate mitochondrial injury and inhibit apoptosis in cardiomyocytes,thus attenuating myocardial I/R injury in rats.%目的 通过评价磷脂酰肌醇-3-激酶/丝氨酸-苏氨酸激酶(PI3K/Akt)信号通路与线粒体通透性转换孔(mPTP)的关系,探讨舒芬太尼后处理减轻大鼠心肌缺血再灌注损伤的机制.方法 清洁级健康雄性SD大鼠48只,3月龄,体重250～ 300 g,采用随机数字表法分为4组(n=12):假手术组(S组)、心肌缺血再灌注组(I/R组)、舒芬太尼后处理组(SP组)和舒芬太尼后处理+PI3K抑制剂wortmannin组(SP+W组).采用结扎左冠状动脉前降支30 min,再灌注120 min的方法制备大鼠心肌缺血再灌注损伤模型.SP组和SP+W组于再灌注前5 min舌下静脉注射舒芬太尼1.Oμg/kg,SP+W组于再灌注前5 min静脉注射PI3K抑制剂wortmannin 15 μg/kg,随后给予舒芬太尼1.0μg/kg.于再灌注120 min时取腹主动脉血,测定血清cTnI和CK-MB浓度,随后处死大鼠取心肌组织,采用TUNEL法计数凋亡细胞,计算细胞凋亡指数(AI),分光光度法测定烟酰胺腺嘌呤二核苷酸(NAD+)含量,Western blot法检测磷酸化Akt(p-Akt)的表达;分离心肌细胞线粒体和胞浆,采用Western blot法分别测定细胞色素c(Cyt c)和凋亡诱导因子(AIF)的表达.结果 与S组比较,I/R组、SP组和SP+W组血清cTnI和CK-MB浓度升高,AI增加,NAD+含量降低,p-Akt表达上调,线粒体Cyt c和AIF表达下调,胞浆Cyt c和AIF表达上调(P＜0.05);与I/R组比较,SP组血清cTnI和CK-MB浓度降低,AI减小,NAD+含量升高,p-Akt表达上调,线粒体Cyt c和AIF表达上调,胞浆Cyt c和AIF表达下调(P＜0.05);与SP组比较,SP +W组血清cTnI和CK-MB浓度升高,AI增加,NAD+含量降低,p-Akt表达下调,线粒体Cyt c和AIF表达下调,胞浆Cyt c和AIF表达上调(P＜0.05).结论 舒芬太尼后处理可激活PI3K/Akt信号通路抑制mPTP开放,减轻线粒体损伤,抑制心肌细胞凋亡,从而减轻大鼠心肌缺血再灌注损伤.
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