Objective To investigate the relationship between different ischemic preconditioning protocols and the protective effects of hind limb ischemia/reperfusion injury in rats in purpose of choosing an optimal ischemic pre-conditioning scheme. Methods An experimental study was designed using 40 SD rats divided in five groups ( n=8). Group A: the sham group, laparotomy and separating the abdominal aorta without clamping for 240 minutes ( min) . Group B:ischemia/reperfusion,rats submitted to ischemia for 120 min and reperfusion for 120 min. Group C, D and E:animals submitted to three cycles of clamping and releasing the aorta for 1, 5 and 10 min respectively before being submitted to the ischemia/reperfusion procedure; the oxidative damage, inflammatory and protective effects among five groups were evaluated by measuring serum levels of SOD, MDA, IL-6, TNF-α, IL-10. Results Compared with group B,SOD activities were significantly higher in group D(P<0.05),SOD activities were sig-nificantly higher in group E compared with group D(P<0.05). Compared with group B, the level of IL-6, TNF-α increased obviously in group C, D, E(P<0.05). IL-6, TNF-α, IL-10 was the highest in group E among five groups ( P <0.05 ) . Conclusion The relationship between ischemia preconditioning time and anti-oxidation in hind limb ischemia/reperfusion injury seems paralleled. The inflammatory response accompanied with the ischemia preconditioning becomes serious with ischemia time prolonging. Preconditioning doesn’t show anti-inflammatory effect. Five min/three circulation ischemia preconditioning scheme is an optimal protocol.%目的探讨缺血预处理不同时间方案对肢体缺血再灌注损伤保护作用的差异性,选择合理的缺血预处理时间。方法40只SPF级SD大鼠随机分成5组：假手术组( A组,仅行开腹,分离腹主动脉不阻断)；缺血再灌注组(B组,夹闭腹主动脉缺血2 h后再灌注2 h)；C、D、E组：分别阻断腹主动脉1、5和10 min,再灌注1、5和10 min,重复3个循环后进行2 h缺血2 h再灌注。测定血清超氧化物歧化酶( SOD)、丙二醛(MDA)、白细胞介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)、白细胞介素-10(IL-10)水平,观察各组氧化/抗氧化指标及炎症因子表达的差异性。结果D 组 SOD 活性升高、MDA含量下降,与B组比较差异有统计学意义( P<0.05)；E组改变更明显,和 D 组比较差异有统计学意义(P <0.05)。与B组比较,C、D、E组的IL-6、TNF-α明显升高,差异均有统计学意义(P<0.05)；E组的各炎症因子水平最高,与C组比较差异均有统计学意义( P<0.05)。结论预缺血时间与氧化损伤的保护作用在一定时间窗内呈平行关系,预缺血并无明显抗炎作用,过长时间预缺血甚至能导致全身性炎症反应；5 min/3个循环缺血预处理方案较为适宜。
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