α7亚基烟碱能乙酰胆碱受体激动剂后处理减轻大鼠在体心肌缺血／再灌注损伤最佳干预时间的实验研究

The best interventional time of α7nAChR agonist postconditioning attenuating myocardial isehemia/reperfusion injury in rats

目的观察α7亚基烟碱能乙酰胆碱受体（α7 subunit-containing nicotinicacetylcholinereceptor，α7nAChR）激动剂后处理减轻大鼠在体心肌缺血，再灌注损伤（ischemia／reperfusioninjury，I／RI）的最佳干预时间。方法将60只SD大鼠采用计算机产生随机数法分为6组（每组10只）：假手术组（S组）、缺血，再灌注组（I／R组）、再灌注开始时α7nAChR激动剂后处理组（R组）、再灌注30、60、90min时α7nAChR激动剂后处理组（P30组、P60组和P90组）。实验结束测定再灌注180min时的肿瘤坏死因子-α（TNF-α）、高迁移率族蛋白B1（highmobicitygroupbox1，HMGB1）和肌钙蛋白Ⅰ（troponinl，TnI）血清浓度，实验取心脏采用伊文蓝和TYC双重染色法测量心肌梗死面积。结果I／R组、P0组、P30组、P60组和P90组的心肌梗死面积值（infarctsize，IS％）分别是（78±16）、（60±7）、（49±17）、（54±12）和（64±15）％，并且5组的血清TnI浓度分别是（1．016±0．121）、（0．168±0．037）、（0．156±0．019）、（0．194±0．041）和（0．138±0．029）μg／L。与S组相比，I／R组和P30组的TNF电血清浓度显著增高，P0组的TNF电浓度显著降低；I／R组的HMGBl血清浓度显著增高，而全部α7nAChR激动剂后处理组的HMGBl血清浓度显著降低。与I／R组相比，全部α7nAChR激动剂后处理组的IS％显著减小以及TnI、TNF-α和HMGB1血清浓度显著降低。与P0组相比，P30组、P60组和P90组的TNF-α和HMGBl血清浓度显著增高。与P90组相比，P30组IS％显著减小，其TNF-α和HMGB1血清浓度显著增高。结论在大鼠在体心肌I／RI模型中，再灌注后30min时进行α7nAChR激动剂后处理可获得最佳的心肌保护效应。

Objective To determine the best interventional time of α7nAChR agonist postconditioning for attenuating myocardial ischemia reperfusion injury in rat in vivo model. Methods Sixty SD rats were randomly divided into six groups（n=10）： sham group （S group）, ischemia/reperfusion group （I/R group）, α7nAChR agonist postconditioning at onset of reperfusion group（P0 group）, α7nAChR agonist postconditioning at 30, 60 and 90 min of reperfusion group（P30, P60 and P90 groups）. Serum concentrations of TnI, TNF-αand HMGB1 were assayed at 180min after reperfusion. At the end of experiment, infarction sizes were assessed from excised hearts by Evans blue and triphenyltetrazolium chloride（TTC） staining. Results The infarct sizes（IS%） were （78±16）% in IR group, （60±7）% in Po group, （49±17）% in P3o group, （54±12）% in P60 group and （64±15）% in P90 group, respectively. Serum concentrations of TnI were （1.016±0.121）, （0.168±0.037）, （0.156±0.019）, （0.194±0.041） and（0.138±0.029）μg/L in these groups respectively. As compared to the S group, serum concentrations of TNF-α in the I/R and P30 groups were significantly increased, TNF-α in the P0 group was significantly reduced. Serum concentration of HMGB1 was significantly higher in the I/R group than that in the S group, but that of all α7nAChR agonist postconditioning groups was significantly lower. As compared with the I/R group, infarct size and serum concentrations of TnI, TNF-α and HMGB1 in all α7nAChR agonist postconditioning groups were significantly reduced. As compared with the Pogroup, serum concentrations of TNF-α and HMGB1 in the P30, P60 and P90groups were significantly increased. As compared with the P90 group, in the P30 group, serum concentrations of TNFα and HMGB1 were significantly increasedand IS% significantly decreased. Conclusion In rat in vivo models of myocardial ischemia reperfusion injury, α7nAChR agonist postconditioning at 50 min of reperfusion could produce the strongest cardioprotection.