JAK-STAT信号通路在离体大鼠心肌缺血再灌注损伤激活时程的研究

目的观察JAK-STAT信号通路在离体大鼠心肌缺血再灌注损伤过程中激活的时程及意义。方法采用Langendorff离体灌流模型,将42只雄性Wistar大鼠随机分为7组:对照组:用改良的KH液持续灌流180 min;I/R组:按再灌注时间分为R0、R5、R15、R30、R60、R120 6组,用改良的KH液灌流平衡30 min后,全心停灌30 min,分别再灌注0、5、15、30、601、20 min。连续监测左室发展压(LVDP)、左室压力最大升降速度(+dp/dtmax)以评价心功能,采用改良的Gonori变色酸(GCA)亮绿特殊染色法观察心肌缺血程度;免疫印迹法检测再灌注不同时程磷酸化的STAT1、STAT3蛋白表达的变化。结果与对照组相比,再灌注不同时程LVDP及+dp/dtmax明显降低((P<0.01),GCA特殊染色显示缺血变性的心肌细胞数量明显增多(P<0.01),再灌注各时程STAT1、STAT3均处于激活状态,与对照组相比差异有统计学意义(P<0.01)。但二者表达存在时间差异,p-STAT1在缺血30 min增高不明显,再灌注过程中处于显著激活状态(P<0.01);p-STAT3在缺血30 min即明显升高(P<0.01),而再灌注期未见进一步升高(P>0.05),p-STAT1/p-STAT3与LVDP及GCA特殊染色阳性率呈显著的相关性。结论JAK-STAT信号通路参与了心肌缺血再灌注损伤的发生,磷酸化的STAT1与STAT3的比例可能决定了再灌注损伤的严重程度。

The time course of activation of JAK-STAT signal pathway during ischemia/reperfusion injury in isolated rat heart

ObjectiveTo investigate time course and significance of activation of JAK-STAT signal pathway during ischemia/reperfusion injury in isolated working rat heart.MethodsUsing Langendorff isolated perfused heart model,the hearts from 42 Wistar male rats were randomly divided into 7 groups,8 rats in each group.In control group,the hearts were perfused with motified Krebs-Henseleit buffer for 180 minutes;in ischemia/reperfusion group,the hearts were divided into 6 groups radomly according to the time course of reperfusion(R0,R5,R15,R30,R60,R120),hearts were perfused with motified Krebs-Henseleit buffer for 30 minutes,followed by 30 minutes of global ischemia and 0,5,15,30,60,120 mintues of reperfusion respectively.Then LV developed pressure(LVDP),the peak positive first derivative of LV pressure( dp/dtmax) were all derived or calculated from the continulously monitored pressure singal.Modified Gonori chromotropic acid bright green specific staining and immunoblotting were used for detecting pathological change and the protein expression of phosphorylation of STAT1 and STAT3 in myocardial tissue at different time point during ischemia/reperfusion.ResultsCompared to control group,LVDP and dp/dtmax significantly decreased and degenerative myocardial cells remarkablely increased by specific staining at different time points during reperfusion(P<0.01).STAT1 and STAT3 were all stayed in activated state during reperfusion,there was significant difference compared to control group(P<0.01).However,the expression of phosphorylation of STAT1 and STAT3 differed in the time course.Phosphorylation of STAT1 was of no remarkable elevation at 30 min post-ischemia,it increased significantly and occupied persistent activated state at every time point during reperfusion(P<0.01),phosphorylation of STAT3 rised significantly as early as 30 min post-ischemia(P<0.01),but there was no continuous elevation during reperfusion.Phosphorylation of STAT1 and the proportion between p-STAT1 and p-STAT3 correlated dramatically with LVDP and positive percent of degenerative myocardial cells(r=-0.921,r=0.969).ConclusionJAK-STAT signal pathway participated in pathological course of I/R injury.The proportion between STAT1 and STAT3 might determine the extent of I/R injury.