缺血预适应对肺缺血-再灌注损伤中细胞凋亡与热休克蛋白70表达的影响

目的 观察缺血预适应(IP)对在体大鼠肺缺血-再灌注(I/R)损伤细胞凋亡及热休克蛋白(HSP70)表达的影响,探讨其作用的可能机制.方法 雄性SD大鼠36只,随机分为3组:假手术(SO)组,缺血.再灌注(I/R)组,缺血预适应(IP)组,每组12只.I/R组开胸后用无创微血管钳钳夹肺门远心端,阻断肺门(观察肺无舒缩为阻断标准),建立在体肺脏L/R损伤模型.IP组于缺血开始前,应用3个循环的5min缺血+5 min灌注进行预处理.假手术组仅予开胸术.各组均于2h、5 h时结扎肺门取出左肺.用原位末端标记法(TUNEL)检测细胞凋亡指数,免疫组化法测定HSPT0表达.计算肺湿干比(W/D),肺泡损伤数定最评价指标(IQA),同时在光镜与电镜下观察肺脏的病理形态学和超微结构的改变.为应用单因素方差分析,组间两两比较采用scheffe检验.结果 与SO组比较,I/R组凋亡指数2 h点为21.37±4.35、5h点为19.67±3.64,均增加(P=0.000),HSP 70表达2 h点为0.187±0.019、5 h点为0.207±0.021均增加(P=0.000),W/D 2 h点为6.65±0.85、5 h点为7.10±0.94,均增加(P=0.000),IQA 2 h点为45.95±2.82、5 h点为55.77±3.24均显著升高(P:0.000).与I/R组比较,IP组凋亡指数2 h点为14.02±3.15(P=0.005)、5 h点为12.18±2.29(P=0.001),均明显下降,HSP70表达2 h点为0.240±0.017(P=0.000)、5 h点为0.260±0.022(P=0.002),均增强,W/D 2 h点为5.39±0.36(P=0.074)、5 h点为5.47±0.44(P=0.003),有不同程度降低、IQA 2 h点为25.77±3.77、5 h点为30.35±3.69,差异具有统计学意义(P=0.000).肺脏超微结构损害和肺水肿程度明显减轻.结论 缺血预适应对肺缺血.再灌注损伤有保护作用,其机制可能是通过上调HSP70的表达而抑制细胞凋亡来实现的.

Effect of ischemic preconditioning on pneumocyte apoptosis and the expression of HSP70 during pulmonary ischemia-reperfusion injury in rats

Objective To investigate the effects of ischemic preconditioning on pneumocyte apoptosis and the expression of HSFT0 after lung isehemia-reperfusion(I/R) in rats and discuss its possible mechanism of extenu-ating ischemia-repedusion injury. Method Thirtysix male Sprague-Dawley rats were randomly divided into three groups sham operation(SO ) group, ischemia-teperfusion(L/R) group, and ischemic preconditioning(IP) group],twelve in each group. Lung croas-clamping was used to build the L/R model. In IP group, three cycles of 5-minute-ischemia + 5-minute-reperfusion were given to the pulmonary artery before the procedure. Sham operation rats had a thoracotomy only. Two hours(or five hours) reperfusion was given to both L/R and IP group. Tenninal-deoxynucleotidyl Transferase Mediated d-UTP Nick End Labeiing(TUNEL) was used to evaluate apoptosis. Expression of HSP/0 in lung was observed by immunohistochemical stain and image analysis. Index of quantitative assessment of histologic lung injury(IQA), wet to dry weight ratio(W/D) were measured. The pathological change of lung tissue was observed under both hght and electron microscopy. Statistical analysis was carried out by One-way Anova. Scheffe test was used for intragroup comparison. Results The apoptosis index and expression of HSP70、W/D,IQA of hng tissue in I/R group were higher than those in the sham operation group (P<0.01). Compared with the L/R group, the apoptosis index and expression of HSP70, W/D, IQA of lung tissue significantly decreased (P<0.01), the levels of expression of HSPTO increased significantly in IP group ( P<0.01 ). The pathological and ultrastructure change of lung tissue was better in IP group than those in I/R group. Condusions Ischemic preconditioning can extenuate lung I/R injury by the possible mechanism of increasing the expression of HSPT0 which inhibits the apoptosis during lung I/R injury.