p38丝裂原活化蛋白激酶通过下调肌质网Ca^2+ ATP酶2α参与大鼠心肌缺血/再灌注损伤

Involvement of p38 mitogen?activated protein kinase in myocardial ischemia/reperfusion injury through down?regulating sarcoplasmic/endoplasmic reticulum Ca^2+ATPase 2αin rats

目的探讨p38丝裂原活化蛋白激酶(p38 mitogen activated protein kinase,p38MAPK) 肌质网Ca^2+ ATP酶2α(sar coplasmic/endoplasmic reticulum Ca^2+ATPase 2α,SERCA2α)信号通路在大鼠心肌缺血/再灌注损伤(ischemia/reperfusion injury,I/RI)中的作用。方法采用随机数字表法将45只雄性SD大鼠(体重250~300 g)分为A组、B组和C组(每组15只),其中A组用于测定心肌梗死面积,B组用于检测心肌组织p38MAPK和SERCA2α蛋白量,C组用于检测心肌组织SERCA2αmRNA。分别将A组、B组和C组组内大鼠按随机数字表法分为3组(每组5只):假手术组(Sham组)、缺血/再灌注(ischemia/re perfusion,I/R)组(I/R组)、I/R+SB203580组(I/R+S组)。I/R+S组于术前1 h腹腔注射p38MAPK抑制剂SB203580(2 mg/kg),其余两组于术前1 h仅注射等体积生理盐水。采用结扎冠状动脉左前降支(left anterior descending,LAD)30 min后再灌注10 min的方法建立大鼠心肌I/RI动物模型。再灌注结束后,动脉血气分析法监测大鼠内环境状态,Western blot法检测心肌组织磷酸化p38MAPK(phospho p38MAPK,p p38MAPK)、SERCA2α蛋白水平,实时荧光定量PCR(real time quantitative PCR,RT qPCR)法检测心肌组织SERCA2αmRNA水平,伊文蓝及2,3,5 氯化三苯基四氮唑(2,3,5 triphenyl tetrazolium chloride,TTC)双染色法测定心肌缺血和心肌梗死面积。结果各组大鼠血气分析结果差异无统计学意义(P>0.05)。与Sham组比较,I/R组与I/R+S组心肌梗死面积与心肌组织中p p38MAPK蛋白水平明显增加(P<0.05)、SERCA2α蛋白及mRNA水平明显降低(P<0.05)。与I/R组比较,I/R+S组心肌梗死面积明显减少、p p38MAPK蛋白水平明显降低(P<0.05),SERCA2α蛋白和mRNA水平明显升高(P<0.05)。结论p38MAPK可能通过介导SERCA2α参与大鼠心肌I/RI。

Objective To investigate the effects of p38 mitogen activated protein kinase(p38MAPK) sarcoplasmic/endoplas mic reticulum Ca^2+ATPase 2α(SERCA2α)signaling pathway on myocardial ischemia/reperfusion injury(I/RI)in rats.Methods Forty five male SD rats(250?300 g in weight)were divided into three groups according to the random number table method(n=15):group A,group B and group C.Group A was used to measure the size of myocardial infarct.Group B was adopted to determine the levels of p38MAPK and SERCA2αprotein in myocardial tissues.Group C was used to examine the expression of SERCA2αmRNA in myocar dial tissues.Then,rats in groups A,B and C were divided into three groups by the random number table method respectively(n=5):a sham operated group(group sham),an ischemia/reperfusion(I/R)group(group I/R),and an ischemia/reperfusion+SB203580 group(group I/R+S).Group I/R+S was intraperitoneally injected with p38MAPK inhibitor SB203580(2 mg/kg)1 h before surgery,while the other two groups were injected with an equal volume of normal saline 1 h before surgery.A model of myocardial I/RI was established in rats through ligation of the left anterior descending(LAD)coronary artery over 30 min before reperfusion for 10 min.After the end of re perfusion,blood gas analysis was performed to monitor the internal environment of rats.Western blot was used to detect the expression of phospho p38MAPK(p p38MAPK)and SERCA2αprotein in myocardial tissues.Real time quantitative PCR(RT qPCR)was used to detect the expression of SERCA2αmRNA in myocardial tissues.Myocardial ischemia and infarct size were measured by Evans blue and 2,3,5 triphenyl tetrazolium chloride(TTC)double staining.Results There was no statistical difference in the results of gas blood analysis among the three groups(P>0.05).Compared with group sham,groups I/R and I/R+S presented remarkable increases in myocardial infarct size and the levels of p p38MAPK protein(P<0.05),and marked decreases in the levels of SERCA2αprotein and mRNA(P<0.05).Compared with group I/R,group I/R+S produced remarkably decreased myocardial infarct size and p p38MAPK pro tein levels(P<0.05),and marked increased amounts of SERCA2αprotein and mRNA(P<0.05).Conclusions p38MAPK may be in volved in myocardial I/RI in rats through mediating SERCA2α.