STAT3信号转导通路在二氮嗪心脏停搏液减轻大鼠离体心脏缺血再灌注损伤中的作用

Role of STAT3 signal transduction pathway in diazoxide cardioplegic solution-induced reduction of ischemia-reperfusion injury in isolated rat hearts

目的 评价STAT3信号转导通路在二氮嗪心脏停搏液减轻大鼠离体心脏缺血再灌注损伤中的作用.方法 健康雄性SD大鼠,2～3月龄,体重240 ～ 260 g,采用Langendorff装置制备离体心脏灌注模型.取模型制备成功的心脏60个,采用随机数字表法分为5组（n=12）：对照组（C组）平衡灌注15 min后继续灌注90 min；缺血再灌注组（IR组）、常规心脏停搏液组（P组）、二氮嗪心脏停搏液组（DZX组）和STAT3抑制剂Stattic组平衡灌注15 min,停灌30 min后恢复灌注.P组停灌前以含0.4％ DMSO的钾镁心脏停搏液灌注5 min；DZX组停灌前以含50μmol/L二氮嗪的钾镁心脏停搏液灌注5 min；Stattic组灌注含二氮嗪的钾镁心脏停搏液前以10μmol/L Stanic灌注5 min.于再灌注60 min时制备心脏切片,染色后测定梗死面积,计算心肌梗死面积百分比,采用TUNEL法检测凋亡细胞,计算凋亡指数,Western blot法检测磷酸化STST3 （p-STAT3）蛋白表达,PCR法检测STAT3 mRNA表达.结果 与C组比较,其余4组心肌梗死面积百分比和凋亡指数升高,IR组和Stattic组心肌p-STAT3蛋白和STAT3 mRNA表达下调,P组和DZX组心肌p-STAT3蛋白表达下调,STAT3 mRNA表达上调（P＜0 05）；与IR组比较,P组和DZX组心肌梗死面积百分比和凋亡指数降低,心肌p-STAT3蛋白和STAT3mRNA表达上调（P＜0.05）,Stattic组上述指标差异无统计学意义（P＞0.05）；与P组比较,DZX组心肌梗死面积百分比和凋亡指数降低,心肌p-STAT3蛋白和STAT3 mRNA表达上调（P＜0.05）.结论 STAT3信号转导通路参与了二氮嗪心脏停搏液减轻大鼠离体心脏缺血再灌注损伤的过程.

Objective To evaluate the role of signal transducer and activator of transcription 3 （STAT3） signal transduction pathway in diazoxide cardioplegic solution-induced reduction of ischemia-reperfusion （I/R） injury in isolated rat hearts.Methods Sixty adult male Sprague-Dawley rats,aged 2-3 months,weighing 240-260 g,were used in this study.Their hearts were excised and perfused in a Langendorff apparatus and then randomly divided into 5 groups （n=12 each）：control group （group C）,group I/R,cardioplegic solution group （group P）,diazoxide cardioplegic solution group （group DZX）,and STAT3 signal transduction pathway blocker Stattic group （group Stattic）.The hearts were continuously perfused for 90 min after 15 min of equilibration in group C.Perfusion was stopped after 15 min of equilibration and restored 30 min later in I/R,P,DZX and Stattic groups.In P and DZX groups,the hearts were perfused with the cardioplegic solution containing 0.4％ dimethyl sulfoxide and 50μmol/L diazoxide,respectively,before perfusion was stopped.In group Stattic,the hearts were perfused with 10μmol/L Stattic for 5 min before perfusion with diazoxide.At 60 min of reperfusion,the hearts were sliced and stained for determination of myocardial infarct size （IS） as a percentage of area at risk （AAR） （IS/AAR）,cell apoptosis and expression of phosphorylated STAT3 （p-STAT3） protein （by Western blot） and STAT3 mRNA （using RT-PCR）.Apoptotic index （AI） was calculated.Results Compared with group C,the IS/AAR and AI were significantly increased in the other four groups,the expression of p-STAT3 and STAT3 mRNA was down-regulated in I/R and Stattic groups,and the expression of p-STAT3 was down-regulated and STAT3 mRNA was up-regulated in P and DZX groups （P ＜ 0.05）.Compared with group I/R,the IS/AAR and AI were significantly decreased,and the expression of p-STAT3 and STAT3 mRNA was up-regulated in P and DZX groups （P ＜ 0.05）,and no significant changes were found in the parameters mentioned above in Stattic group （P ＞ 0.05）.The IS/AAR and AI were significantly lower,and the expression of p-STAT3 and STAT3 mRNA was higher in DZX group than in P group （P ＜ 0.05）.Conclusion STAT3 signal transduction pathway is involved in diazoxide cardioplegic solution-induced reduction of I/R injury in isolated rat hearts.