一氧化氮合酶抑制剂对鼠脑缺血再灌注后线粒体呼吸功能的保护作用

Protective effects of nitro oxide synthase inhibitor on mitochondrial respiratory function after cerebral ischemic reperfusion

目的观察鼠脑缺血和再灌注后脑细胞线粒体呼吸功能的改变，以及应用一氧化氮合酶抑制剂ＮＧ位硝基左旋精氨酸（ＬＮＮＡ）后对线粒体呼吸功能的保护作用。方法采用沙土鼠双侧颈总动脉夹闭３０分钟再开放，造成脑缺血再灌注模型（１３４只鼠），测定脑缺血及再灌注１、３、６、２４、４８小时线粒体呼吸３、４态，呼吸控制率（ＲＣＲ）和磷氧比（Ｐ／Ｏ比值），评价线粒体呼吸功能（ＭＲＦ）；并观察不同时间给予ＬＮＮＡ后ＭＲＦ的改变。结果脑缺血３０分钟ＭＲＦ受抑制，ＲＣＲ特别是呼吸３态明显下降；再灌注早期ＭＲＦ有所恢复，呼吸３态升高，而再灌注后期呼吸４态明显上升，ＲＣＲ再次下降。再灌注１小时后给予ＬＮＮＡ可降低呼吸４态，ＲＣＲ高于再灌注对照组；再灌注时给予ＬＮＮＡ对ＭＲＦ无影响。结论再灌注后ＭＲＦ进一步受损，无效耗氧增加，内源性一氧化氮的过量产生对线粒体具有毒性效应，且于再灌注１～２小时后出现；ＬＮＮＡ对再灌注后ＭＲＦ具有保护作用。

Objective To observe the change of mitochondrial respiratory function of the brain cells and the protective effect of LNNA (nitric oxide sythase inhibitor). WT5”HZ〗Methods We measured the brain mitochondrial respiratory state 3 and state 4, the respiratory control rate(RCR) and the phosphor oxygen ratio(P/O) in cerebral ischemia and 1, 3, 6, 24 and 48 h after reperfusion, in order to evaluate mitochondrial respiratory function(MRF). Also we observed the changes of MRF after being given LNNA at various periods of time. Results MRF was inhibited in 30 minites after ischemia. The RCR, especialy in state 3, had obviously decreased; The RCR recovered and state 3 increased in the early time after reperfusion. This led to decreasing of RCR again. State 4 decreased after being given LNNA at various periods of time 1 h after reperfusion and RCR was higher than that of the reperfusion control; MRF was not changed after being given LNNA in the begining of reperfusion. Conclusions MRF was further damaged after reperfusion and noneffective oxygen consumption was increased. The overproduction of endogenous nitric oxide (NO) had toxic effects on the mitochondria 1～2 h after reperfusion. LNNA might be able to protect MRF after reperfusion.