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探讨低氧时一氧化氮 (NO)、一氧化氮合酶 (NOS)变化及发生变化的机理。方法 :大鼠分为常氧对照组、间断低氧习服组和急性低氧组。分别测定脑、肺NO、NOS及NOS催化反应平衡常数 (Keq)。结果 :与常氧对照比较 ,低氧大鼠 (急性低氧组 ,低氧习服组 )脑、肺NO水平明显下降 (P <0 .0 1) ;急性低氧组NOS活力明显下降 (P <0 .0 1) ,而间断低氧习服组NOS活和下降不明显 (P >0 .0 5 )。急性低氧组与低氧习服组比较 ,前者NOS活力明显低于后者 (P <0 .0 1)。低氧时NOS催化反应平衡常数出现左移。结论 :低氧时NO水平及NOS活力下降 ,经低氧习服后 ,NO水平及NOS活力可明显改善 ;NOS催化反应平衡常数发生变化是NO水平及NOS活力下降的原因之一。
To investigate the changes of nitric oxide (NO), nitric oxide synthase (NOS) and its mechanism during hypoxia. Methods: Rats were divided into normoxic control group, intermittent hypoxic preconditioning group and acute hypoxia group. The equilibrium constants of Keq in brain, lung NO, NOS and NOS were measured respectively. Results: Compared with normoxia control group, NO levels in brain and lung of hypoxic rats (acute hypoxia group and hypoxic preconditioning group) decreased significantly (P <0.01); NOS activity in acute hypoxia group decreased significantly (P <0.01), while the NOS activity and decline in intermittent hypoxic preconditioning group were not significant (P> 0.05). The activity of NOS in acute hypoxic group was significantly lower than that in hypoxic preconditioning group (P <0.01). Hypoxia NOS catalytic reaction equilibrium constant shift to the left. CONCLUSION: The levels of NO and NOS in hypoxia decrease. After hypoxia, the level of NO and the activity of NOS can be remarkably improved. The change of NOS catalytic equilibrium constant is one of the reasons for the decrease of NO level and NOS activity.