The study is to investigate the dynamic expression of nitric oxide synthase(NOS) in primary cultured rat cortical neurons following hypoxia reoxygenation(H/R) and the effects of extract of ginkgo biloba(EGB) on the expression of NOS in order to explore the role of NO in H/R induced neuronal damage and the mechanisms of EGB's neuronal protection. Primary culture of E16~17 days fetal rat cortical neurons was used to establish H/R injury model. There were 4 groups : (1)normal control group, (2)hypoxia only gr...