JAK2-STAT3通路对七氟烷后处理在体大鼠缺血/再灌注心肌的影响

The influence of JAK2/STAT3 pathway in the cardioprotection of postconditioning by sevoflurane against myocardial ischemia-reperfusion injury in rat in vivo

目的探讨Janu激酶/信号转导子和转录激活子(Ja-nus kinase/signal transducer and activator of transcriptio,JAK2/STAT3)通路对吸入七氟烷后处理的在体大鼠缺血/再灌注心肌的保护作用和影响。方法 75只成年健康♂SD大鼠,体质量250～300 g,随机分为5组(n=15):假手术组(S)、缺血/再灌注组(CON)、AG-490组(AG)、七氟烷后处理组(Sev-p)、七氟烷后处理+AG490组(AG+Sev-p)。采用结扎左冠状动脉前降支30 min、再灌注120 min的方法制备心肌缺血/再灌注模型。假手术组左冠状动脉前降支穿线并不阻断冠状动脉,AG-490组在再灌前10 min静注JAK2抑制剂AG-490(3mg·kg-1),七氟烷后处理组在再灌注前2 min开始吸入2.8%七氟烷,持续5 min,七氟烷后处理+AG490组于再灌前10 min静注JAK-STAT通道阻断剂AG-490(3 mg·kg-1),再行七氟烷后处理。各组均以5 ml·kg-1.h-1的速率静脉输注生理盐水维持至术毕。记录心率(HR)、平均动脉压(MAP),计算心率和收缩压乘积(RPP)。各组随机取10只于再灌120 min后处死大鼠,TTC法测定心肌梗死面积(IS/AAR)。各组另5只大鼠,于再灌注开始后的10 min处死,取出左心室心肌组织,提取总蛋白,用Western blot法分析心肌JAK2和磷酸化JAK2及心肌STAT3和磷酸化STAT3的蛋白表达变化。结果与其它组比较,Sev-p组和Sev-p+AG490组在后处理5 min时,MAP、HR和RPP均明显下降(P<0.05),但经历10 min洗脱期后,各指标变化趋向一致,组间比较差异无统计学意义。与CON组和AG+Sev-p组比较,Sev-p组的梗死面积明显减少,差异有统计学意义(P<0.05)。AG-490组与CON组比较心梗面积差异无显著性(P>0.05)。Western blot检测发现,Sev-p组再灌注后10 minJAK2、STAT3的磷酸化水平明显升高,与其它组相比差异有统计学意义,AG+Sev-p组与Sev-p组相比,其JAK2、STAT3的磷酸化水平较低,差异有统计学意义。结论七氟烷后处理对缺血/再灌注损伤的大鼠心肌有较好的保护作用,该作用与JAK2-STAT3通路的激活有关。

Aim To investigate the role and influence of JAK2/STAT3 pathway in the cardioprotection of postconditioning by sevoflurane against myocardial ischemia-reperfusion injury in rats in vivo.Methods Seventy-five healthy male SD rats（250~300 g） were randomly divided into five groups（n=15 each）： Sham-operation group（S）,ischemic reperfusion group（CON）,AG-490 group（AG）,sevoflurane postconditioning group（Sev-p）,sevoflurane postconditioning＋AG-490 group（AG＋Sev-p）.Rats were made into myocardial I/R models produced by occlusion of anterior descending branch of left coronary artery for 30 min followed by 120 min reperfusion.Rats in the sham-operation group were opened the chest to braid for ringer without deligation.In group AG and Sev-p＋AG,AG-490（a specific JAK inhibitor） 3 mg·kg-1 was given iv 10 min before reperfusion.In group（Sev-p） and（Sev-p＋AG）,rats received 2.8% sevoflurane 2 min before reperfusion for 5 min.Saline was infused to each rat at the rate of 5 ml·kg-1·h-1 until the operation was over.HR and MAP were recorded and RPP was calculated.Ten rats were randomly selected from each group,and sacrificed end of 120 min reperfusion for assessment of ischemic and infarct area by triphenyltetrazolium chloride staining.The other five rats were sacrificed 10 min after reperfusion for determination of total and phosphorylated JAK2,STAT3 expression in myocardium by Western blot.Results Compared with other groups,the groups of Sev-p and AG＋Sev-p resulted in a significant reduction of MAP,HR and RPP（P0.05）,but after 10 min of washout,the recovery were similar in each group.The infract areas were significantly smaller in group Sev-p than in others.There were no significant differences in the size of infarct area between group CON and group AG（P0.05）.The phosphorylated JAK-2 and STAT3 expression was significantly higher in group Sev-p than in others（P0.05）.AG-490 could significantly cut down the phosphorylated JAK-2 STAT3 expression（P0.05）.Conclusions Sevoflurance postconditioning effectively protects against myocardial ischemia-reperfusion injury in rats.The JAK2-STAT3 signaling pathway activation is involved in the protective effect.