低氧对大鼠脑、肺组织NO、NOS变化的影响

目的：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、肺组织NO、NOS及NOS催化反应平衡常数（Keq）。结果：与常氧对照组比较，低氧大鼠（急性低氧组，低氧习服组）脑、肺组织NO水平明显下降（P＜0．01）；急性低氧组NOS活力明显下降（P＜0．01），而间断低氧习服组NOS活力下降不明显（P＞0．05）。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＜0．01）。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。

Changes of NO and NOS and Its Mechanism in Rats During Actua and Intermittent Hypoxia

Objective: To study the changes of NO and NOS in rats during hypoxia and discuss its mechanism. Methods. The 24 rats (weight 180-220 g) were divided into three groups: normal control groupe (NC), intermittent hypoxia acclimatization group (IH: exposed to a simuladet altitude of 3 000 m for 2 weeks. 4 hours each day. and then exposed to a simulated altitude of 5 000 no for 2 weeks. 4 hours each day) and acute hypoxia group (AH: exposed to a simulated altitude of 5 000 m for 4 hours) NO, NOS and NOS equivalent coefficience (Keq) in brain and lung were measured. Results; As compared with NC group. the levels of NO in IH and AH groups was lower (P<0. 01); The activity of NOS in AH group had a remarkable drop (P<0. 01) o but it decreased lightly in IH group (P>0. 05). There was obviousl different activity of NOS between IH and AH group (P<0. 01) NOS Keq was found on the decrease during hypoxia. Conclusion; In hypoxic condition, the level intermittent hypoxia acclimatization; the change of NOS Keq was one of the important factors that leaded to the decrease of NO and NOS during hypoxia.