目的　研究一氧化氮 (NO)及一氧化氮合酶 (NOS)抑制剂在大鼠早期缺血性脑损伤中的作用。方法　用线栓法建立大鼠大脑中动脉闭塞模型 ,分别给予非选择性和选择性诱导型NOS抑制剂 ,观察早期缺血性脑损伤过程中脑组织内NO、NOS的变化及作用。结果　非选择性NOS抑制剂可加重脑组织的损伤程度 ,而选择性诱导型NOS抑制剂虽无明显疗效 ,但有防止脑梗塞继续恶化的趋势。结论　来源于不同类型的NOS所合成的NO在早期缺血性脑损伤中具有不同的作用。 Objective To investigate the effects of nitric oxide (NO) and nitric oxide synthase (NOS) inhibitors on early ischemic brain injury in rats. Methods The rat middle cerebral artery occlusion model was established by thread occlusion. Non-selective and selective inducible NOS inhibitor was given respectively to observe the changes of NO and NOS in the brain during early ischemic brain injury. Results Non-selective NOS inhibitors can aggravate the degree of brain damage, while selective induction of NOS inhibitors, although no significant effect, but there is a trend to prevent further deterioration of cerebral infarction. Conclusions NO derived from different types of NOS has different effects on early ischemic brain injury.