缺血预处理对肝硬化大鼠肝脏缺血再灌注损伤保护作用的研究

Ischemic preconditioning attenuates ischemia-reperfusion injury of cirrhotic liver in rats.

目的探讨缺血预处理(IP)对硬化肝脏缺血再灌注损伤的保护作用及其可能机制。方法Wistar雄性大鼠制成肝硬化模型。分两组:IP组离断肝周韧带,消除侧枝循环,用Pringle's法阻断肝门15min,然后恢复血供,关腹;C组只予以开、关腹。48 h后,再次Pringle's法阻断肝门30 min,恢复血供。用Western blotting法测IP后6、24、48 h肝组织中热休克蛋白70(HSP70)表达的水平;测再灌注1、3 h血清生化酶(ALT、AST、LDH)及再灌注3h肝组织中谷胱苷肽(GSH)水平;行病理学观察。结果IP后6 h,两组均有微量HSP70表达,至24-48hIP组HSP70表达显著增强,呈高水平;而C组中在各时点HSP70均无表达增强。再灌注1h,IP组的ALT、AST、LDH水平显著低于C组(P<0.01或P<0.05);再灌注3h,IP组的ALT、AST水平明显低于C组(P<0.01)而其肝组织中的GSH水平明显高于C组(P<0.05)。术后一周生存率IP组(93.10%)明显高于C组(73.33%)(P<0.05)。缺血再灌注后1、3h,IP组的肝细胞损伤明显轻于C组。结论在硬化大鼠肝脏中,IP启动内源性保护机制,诱导HSP70的大量表达,而HSP70通过增加或提高GSH的产生及其活性,清除自由基,减轻硬化肝脏缺血再灌注损伤。

Objective To investigate the protective effect of ischemic preconditioning by Pringle＇s maneuver against ischemia - reperfusion injury of cirrbo - tic livers in rats and its mechanism. Methods Cirrhotic model were induced by subcutaneous injection of carbon tetrachloride （CCI4） in male Wistar rats. Rats were randomized into two groups： the control group rats underwent anesthesia and midline laparotomy only; the ischemic preconditioning （IP） group rats were preconditioned with short- term （15 minutes） hepatic ischemia. After a 48 -hour recovery, all rats were exposed to a longer （30minutes） warm ischemia. Western blotting was used to test the expression of heat shock protein 70 （HSP70） at 6, 24, 48 hours after IP. Serum ALT and AST levels and GSH levels in hepatic tissue were measured at 1, 3 hours and 3 hours respectively after reperfusion. Histology of the liver after reperfusion was also compared. Results HSP70 expression was induced in IP group at greater intensity than that in control group 24 and 48 hours after IP. The survival rate in IP group （93.10%） was significantly higher than that in control group （73.33%, P 〈0.05）. The serum ALT and AST in group IP （481.86±253.79IU/L and 814.86±470.30IU/L, respectively ） 3 hours after reperfusion were significantly lower than those in control group （ 1511 ± 421.50IU/L and 2765.86 ± 1004. 37IU/L, respectively; P 〈 0.01 ） ; while GSH levels in hepatic tissue （ 549.08±40.80 mg/g protein） were significantly higher than those in control group （ 502.79 ±40.80mg/g protein, P 〈 0.05 ）. Compared with control group, hepatic cell damage in IP group was significantly decreased. Conclusion These data indicate that IP can induce HSP70 expression at great intensity, which may increase GSH level or its activity in cirrhotic liver of the rats and protect against ischemia -reperfusion injury in the liver.