摘要目的 探讨线粒体通透性转换孔(mitochondrial permeability transition pore,MPTP)功能状态在α7烟碱型乙酰胆碱受体(α7 nicotinic acetylcholine receptor,α7nAChR)激动剂后处理联合肢体远隔缺血后处理心肌保护效应中的作用. 方法 60只雄性SD大鼠接受左冠状动脉前降支结扎30 min,然后开放结扎实施再灌注120 min.将心肌缺血/再灌注损伤大鼠按随机数字表法分为4组(每组15只):对照组(C组)、PNU282987后处理组(P组)、肢体远隔缺血后处理组(L组)、联合应用PNU282987和肢体远隔缺血后处理组(P+L组).再灌注120 min时采集心肌标本,检测线粒体钙离子保留能力(calciumretention capacity,CRC)反映MPTP功能,采用TUNEL检测缺血区心肌细胞凋亡指数(apoptosis index,AI),采用实时荧光定量PCR(real time quantitative PCR,RQ-PCR)技术检测凋亡相关基因Bcl-2和Bax表达. 结果 与C组相比,P组、L组、P+L组线粒体CRC明显增强(P＜0.05);与P组和L组比较,P+L组线粒体CRC明显增强(P＜0.05).与C组相比,P组、L组和P+L组缺血区心肌细胞AI和Bax mRNA表达明显降低(P＜0.05),Bcl-2 mRNA表达明显增高(P＜0.05);与P组和L组相比,P+L组心肌细胞AI和Bax mRNA表达明显降低(P＜0.05),Bcl-2 mRNA表达增高(P＜0.05). 结论 α7nAChR激动剂后处理和肢体远隔缺血后处理均可通过抑制MPTP开放而减少心肌缺血/再灌注损伤时细胞凋亡,而联合应用两种干预措施可增强对MPTP开放的抑制.

abstractsObjective To assess the role of mitochondrial permeability transition pore (MPTP) in cardioprotection by αt7 nicotinic acetylcholine receptor (α7nAChR) agonist and distal limb ischemia in ischemia/reperfusion injury rats.Methods Sixty male Sprague-Dawley rats received 30 min ligation of the left anterior descending (LAD) coronary artery,followed by 120 min reperfusion.The ischemia/reperfusion injury rats were randomly divided into four groups (n=15):vehicle-treated control group (C group),α7nAChR agonist (PNU282987)-treated group (P group),distal limb ischemia group (L group),PNU282987 and distal limb ischemia group (P+L group).In P group,PNU282987 (2.0 mg/kg) was injected intravenously immediately before reperfusion.After 20 min of LAD ligation in L group,blood flow in the bilateral hind limbs was stopped for 10 min and then resumed before reperfusion.In P +L group,rats received both PNU282987 and distal limb ischemia.The function of MPTP was assessed with mitochondrial calcium retention capacity (CRC) test.Real time quantitative polymerase chain reaction (RQ-PCR) analysis and TUNEL apoptosis test were used to quantify the expression of genes associated with apoptosis and cardiomyocyte apoptotic index.Results Compared to C group,mitochondrial CRC in P,L,P+L groups were significantly increased (P＜0.05).Compared to P and L groups,mitochondrial CRC in P+L group were significantly increased (P＜0.05).The results of RQ-PCR showed that compared to C group,myocardial expression of Bcl-2 mRNA was significantly enhanced in P,L,and P+L groups (P＜0.05),while myocardial expression of Bax mRNA was significantly decreased in P,L,and P+L groups (P＜0.05).The TUNEL apoptosis test showed that cardiomyocyte apoptosis index was significantly decreased in P,L,and P+L groups compared to C group (P＜0.05).Conclusions Both α7nAChR agonist and limb remote ischemia postconditioning can decrease the cardiomyocyte apoptosis by suppressing MPTP opening.Combining two interventions can obtain an enhanced MPTP opening inhibitory effect.