缺血预适应对大鼠肺缺血／再灌注损伤细胞凋亡的影响

Effect of ischemic preconditioning on cell apoptosis in rat with lung ischemia - reperfusion

目的观察缺血预适应（iP）对在体大鼠肺缺血／再灌注（I／R）损伤细胞凋亡及其凋亡相关基因Bcl-2和Bax表达的影响，探讨其作用的可能机制。方法雄性大鼠36只，随机分为三组：假手术（SO）组，缺血／再灌注（I／R）组，缺血预适应（IP）组。I／R组开胸后，建立在体肺脏I／R损伤模型。IP组于缺血开始前，应用3个循环的5min缺血＋5min灌注进行处理，用原位末端标记法（TUNEL）检测细胞凋亡指数，免疫组化法测定Bcl-2和Bax表达。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。结果与SO组比较，I／R组凋亡指数增加，Bax、Bcl-2表达均增强，Bcl-2／Bax比值明显降低。与I／R组比较，IP组凋亡指数明显下降，Bcl-2达增强，Bax表达减弱，Bcl-2／Bax比值增高，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，其作用机制可能是通过调控Bcl-2／Bax介导而减少肺缺血／再灌注细胞凋亡实现的。

Objective To investigate the effects of ischemic preconditioning on cell apoptosis and the expression of Bcl - 2 and Bax in lung vivo after lung ischemia - reperfusion in rats and study the possible role of ischemic preconditioning in the mechanism of attenuating ischemia - reperfusion injury. Meth- ods Thirty - six male Sprague - Dawley rats were randomized into three groups （ twelve for sham opera- tion, twelve for ischemia -reperfusion, twelve for ischemic preconditioning ）. I/R injury consisted of 45 minutes of lung cross - clamping followed by 2 hours （ or 5 hours） of reperfusion; for ischemic precondi- tioning three cycles of 5 minutes of ischema/5 minutes of reperfusion was immediately preceding I/R; sham operation animals had a thoracotomy only. Apoptosis was examined by means of terminal - deoxyrm- cleotidyl transferase mediated d - UTP nick end labeling（TUNEL）. Expression of Bcl -2 and Bax in lung was observed by immunohistochemical stain and image analysis. The dathological change of lung tissue was observed under light microscopy. Electron microscopic evaluation was done on randomly selected lungs of two rats in each group at end of the experiment. Result Compared with the sham opration group, the apoptosis index and expression of Bcl -2 and Bax were higher, and the Bcl -2/Bax ratio decreased significantly in I/R group. Compared with the I/R group, the apoptosis index and the levels of expression of Bax decreased, the expression of Bcl - 2 and the Bcl - 2/Bax ratio increased in IP group. Conclusion Ischemic preconditioning can inhibit the expression of NF - κB after ischemia - reperfusion injury, and attenuate ultrastructure injury of lung tissue, then relieve pulmonary edema, protect from ischemia - reperfusion injury.