线粒体通透性转换孔在α7nAChR激动剂联合远隔缺血后处理心肌保护效应中的作用

Role of mitochondrial permeability transition pore in cardioprotection by combined a7 nicotinic acetyicholine receptor agonist and limb remote ischemia postconditioning

目的探讨线粒体通透性转换孔（mitochondrial permeability transitionpore，Mm）功能状态在or7烟碱型乙酰胆碱受体（α7 nicotinic acetylcholiner eceptor，ct7nAChR）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30min，然后开放结扎实施再灌注120min。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120min时采集心肌标本，检测线粒体钙离子保留能力（calcium retention 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（心0．05）。与c组相比，P组、L组和P＋L组缺血区心肌细胞AI和BaxmRNA表达明显降低（P〈0．05），Bcl-2mRNA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BaxmRNA表达明显降低（P〈0．05），Bcl-2mRNA表达增高（P〈0．05）。结论ctTnAChR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侑｜灌注损伤时细胞凋亡，而联合应用两种干预措施可增强对MWP开放的抑制。

Objective To assess the role of mitochondrial permeability transition pore （MPTP） opening inhibition in cardioprotection by α7 nicotinic acetylcholine receptor （α7nAChR） agonist and limb remote ischemia postconditioning. Methods Sixty male Sprague-Dawley rats were randomly divided into four groups （n=15）： Control group （C group）, PNU282987 postconditioning group （P group）, lime remote ischemia postconditioning group （L group）, combined PNU282987 postconditioning and lime remote ischemia postconditioning group （P＋L group）. In each group, the left anterior descending coronary artery was ligated for 30 min followed by a 120 min reperfusion. In C group, no additional intervention was performed. In P group, α7nAChR agonist, PNU282987 （2.0 mg/kg）, was injected intravenously immediately before a 120-min reperfusion. After 20 min of LAD ligation in L group, blood flow in the bilateral hind limbs was stopped for 10 min and then opened before reperfusion. In P＋L group, rats received the same protocols as those of the L and P groups. The function of MPTP was assessed by 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. Compared to P and L groups, mitochondrial CRC in P＋L group were significantly increased. 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, while myocardial expression of Bax mRNA was significantly decreased in P, L and P＋L groups. The TUNEL apoptosis test showed that cardiomyocyte apoptosis index was significantly decreased in P, L and P＋L groups compared to C group. Conclusions Both α7nAChR agonist and limb remote ischemia postconditioning can decrease the cardiomyocyte apoptosis by suppressing MPTP opening. Combining two interventions can obtained enhances MPTP opening and cardiomyocyte apoptotic inhibitory effects.