BQ123对大鼠肢体缺血再灌注后骨骼肌的保护机制

The mechanism of the protective effect of BQ123 on skeletal muscle after ischemia reperfusion of hind limbs of rats

目的探讨大鼠肢体缺血再灌注(LIR)后骨骼肌细胞损伤变化,以及内皮素A(ETA)受体拮抗剂BQ123对其保护效应的机制。方法雄性Wistar大鼠随机分为对照组(双后肢松弛环绕橡皮圈,不阻断血流),LIR组(结扎大鼠双后肢根部4 h,恢复血流灌注4 h)和BQ123处理组(松带前15 min给予BQ123 7μg/kg,其他操作同LIR组),每组8只。检测肢体缺血4 h再灌注4 h后各组骨骼肌组织中一氧化氮(NO)、内皮素(ET-1)以及NO/ET-1、活性氧(ROS)、髓过氧化物酶(MPO)、Ca2+、Na+-K+-ATP酶、Ca2+-ATP酶;采用原位脱氧核糖核甘酸末端转移酶介导的缺口末端标记法(TUNEL)检测各组腓肠肌细胞的凋亡情况。结果 LIR组与对照组相比较,骨骼肌组织NO、ET-1、ROS、MPO和Ca2+含量均增加,NO/ET-1比值减小,Na+-K+-ATP酶、Ca2+-ATP酶活性降低,凋亡指数(AI)明显增高(P<0.01);与LIR组比较,BQ123组骨骼肌组织NO含量升高,ET-1、ROS、MPO和Ca2+含量下降,NO/ET-1比值升高,Na+-K+-ATP酶、Ca2+-ATP酶活性升高,AI下降(P<0.01)。结论 BQ123对大鼠LIR后骨骼肌的保护作用与其拮抗ET-1的作用,改善微循环、减轻氧化损伤、细胞内钙超载有关。

Objective To observe the injury of skeletal muscle after limbs ischemia reperfusion （ LIR） in rats and to investigate the protective mechanism of endothelin-A receptor antagonist BQ 123 on the skeletal muscle after LIR .Methods The male Wistar rats were randomly divided into three groups ,with 8 rats in each group：control group （ rubber band around the hind limbs relaxed,without blocking blood flow）,LIR group（subjected to 4h of hind limb ischemia and 4h reperfusion）, BQ123 treatment group（pretreated with BQ123 7μg/kg 15 minutes before reperfusion）.The contents of initric oxide（NO）, endothelin-1（ET-1）,NO/ET-1,reactive oxygen species（ROS）,myeloperoxide（MPO）,Ca2＋,Na＋-K＋-ATPase and Ca2＋-ATP ase in skeletal muscle were detected .Apoptosis condition was examined by means of TdT-mediated dUTP nick end labeling （TUNEL）.Results As compared with those in control group ,the contents of NO,ET-1,ROS,MPO and Ca2＋in skeletal muscle tissue were significantly increased in LIR group ,however,the levels of NO/ET-1,activities of Na ＋-K＋-ATPase and Ca2＋-ATPase were decreased,and apoptosis index （AI） was significantly increased （ P 〈0.01）.As compared with those in LIR group, the contents of NO were increased , the levels of ET-1, ROS, MPO and Ca2＋ in skeletal muscle tissue were decreased,the ratio of NO/ET-1 and the activities of Na ＋-K＋-ATPase,Ca2＋-ATPase were obviously increased,but AI was significantly decreased in BQ123 treatment group（ P 〈0.01）.Conclusion The protective effect of BQ123 on skeletal muscle of rats after LIR may be related with its effects of antagonizing ET-1,improving microcirculation ,alleviating oxidative damage and the calcium overload in cells .