二氮嗪后处理对缺血/再灌注心肌的保护作用及其与PI3K/Akt信号通路的关系

目的研究PI3K/Akt信号通路是否参与二氮嗪后处理减轻大鼠心肌缺血/再灌注(I/R)损伤。方法 60只♂SD大鼠随机分为5组(n=12):假手术组(S组)、I/R组、二氮嗪(D组)、wortmannin组(W组)、二氮嗪+wortmannin组(D+W组)。建立大鼠在体心脏I/R模型,除S组外,其余各组均缺血30 min,再灌注120 min。再灌注前5 min,5组分别依次经股静脉输注0.1%DMSO、0.1%DMSO、二氮嗪7mg.kg-1、wortmannin 15μg.kg-1和二氮嗪7 mg.kg-1,其中D+W组于给予二氮嗪前5 min输注wortmannin 15μg.kg-1。记录缺血前、缺血30 min和再灌注120 min时心率(HR)、左室发展压(LVDP)、左室舒张末压(LVEDP);再灌注末,2,3,5-氯化三苯基四氮唑(TTC)染色法检测心肌梗死面积、TUNEL染色法检测心肌细胞凋亡率、Western blot分析p-Akt表达水平。结果各组缺血前心功能指标HR、LVDP、LVEDP无差异(P>0.05)。再灌注120 min后,与I/R组相比,D组和D+W组LVDP明显升高、LVEDP明显降低(P<0.01或<0.05),梗死面积与凋亡率降低(P<0.01或0.05),D组p-Akt表达水平升高(P<0.01);与D组比,D+W组LVDP降低(P<0.05),梗死面积与凋亡率增高(P<0.05),p-Akt表达水平降低(P<0.01)。结论二氮嗪后处理部分通过激活PI3K/Akt信号通路减轻大鼠在体心肌I/R损伤。

Protective effect against myocardial ischemia/reperfusion induced by diazoxide-postconditioning and its interaction with PI3K/Akt signaling pathway

Aim To explore whether the phosphatidylinositol 3-kinase/protein kinase B(PI3K/Akt) signaling pathway was involved in diazoxide-postconditioning-induced protection against cardiac ischemia/reperfusion(I/R) injury in rats.Methods 60 male SD rats were randomly divided into five groups(n=12):sham operation group(S group),I/R group,diazoxide group(D group),wortmannin group(W group) and diazoxide+wortmannin group(D+W group).Myocardial I/R model was induced in rats,and all animals were subjected to 30 min ischemia followed by 120 min reperfusion except S group.Every group was infused respectively with 0.1% DMSO,0.1% DMSO,diazoxide 7 mg·kg-1,wortmannin 15 μg·kg-1 and diazoxide 7 mg·kg-1 through the femoral vein 5 min before reperfusion,and wortmannin was given 5 min before the administration of diazoxide in D+W group.Heart rate(HR),left ventricular developed pressure(LVDP),left ventricular end-diastolic pressure(LVEDP) were recorded just before ischemia,and at the time of 30 min ischemia and 120 min reperfusion.Myocardial infarct size was measured by triphenyltetrazolium chloride(TTC) staining,TUNEL staining was used to detect apoptotic rate of myocardial cells,and the expression of p-Akt in myocardial tissue was measured with Western blot analysis at the end of reperfusion.Results There was no difference in hemodynamics(HR,LVDP,LVEDP) among different groups before ischemia(P>0.05).Compared with I/R group,LVDP was increased significantly and LVEDP was decreased significantly in group D and D+W(P<0.01 or <0.05);myocardial infarct size and apoptotic rate in group D and D+W were significantly reduced(P<0.01 or <0.05);the expression of p-Akt in D group was increased markedly(P<0.01).Compared with group D,LVDP in D+W group was significantly decreased(P<0.05),the myocardial infarct size and apoptotic rate of myocardial cells in D+W group were increased markedly(P<0.05),with lower expression of p-Akt(P<0.01).Conclusion Diazoxide postconditioning reduces myocardial I/R injury in rats partly via activating PI3K/Akt signaling pathway.