Objective To investigate the effects of combination of propofol and whole-body hypoxic preconditioning on lung ischemia-reperfusion(I/R)injury in rats and the mechansim involved.Methods Ninety male SD rats weighing 250-320 g,were randomly divided into 5 groups(n=18 each): sham operation group(group S),lung I/R group(group I/R),propofol preconditioning group(group P),whole-body hypoxic preconditioning group(group WBHP),and combination of propofol and whole-body hypoxic preconditioning group(group PW).The animals were anesthetized with intraperitoneal 3% pentobarbital 30 mg/kg,tracheostomized and mechanically ventilated.Lung I/R injury was produced by occlusion of hilum of the left lung for 45 min followed by reperfusion.Propofol was continuously infused iv at 30 mg·kg-1·h-1 30 min before ischemia in group P.In group WBHP,5 times of WBHP were performed before ischemia.In group PW,propofol was infused iv at 30 mg· kg-1·h- 1 and 5 times of WBHP were performed 30 min before ischemia.Six rats from each group were killed at 30 min,1 h,and 4 h of reperfusion(T1-3).The lungs were then removed for determination of the contents of TNF-α,IL-1,IL6 and MDA,and activities of SOD.The W/D lung weight ratio was calculated.Results Compared with group S,the contents of TNF-α,IL-1,IL-6 and MDA and W/D ratio were significantly increased at T1-3,and SOD activity was significantly decreased at T1-3 in the other four groups(P＜0.05).The contents of TNF-α,IL-1,IL-6 and MDA and W/D ratio were significantly lower at T1-3 ,and SOD activity was significantly higher at T1-3 in group P,WBHP and PW than in group I/R(P ＜ 0.05).The contents of TNF-α and IL-6 and W/D ratio at T2,3 and contents of IL-1 and MDA at T3 were significantly lower,and SOD activity was significantly higher at T2,3 in group PW than in group P and WBHP(P＜0.05).There was no significant difference in the parameters metioned above between group P and WBHP(P＞0.05).Conclusion The combination of propofol and WBHP can protect the lungs from I/R injury,the efficacy is better than that of either of them alone,and it may be related to the enhancement in the inhibiton of inflammatory reaction and improvement in the antioxidant effect.