目的：了解氯胺酮对大鼠脑ＮＯＳ活性和ＮＯ产量的影响。方法：１６只ＳＤ大鼠，随机分为二组，分别ｉｐ生理盐水１０ｍｌ／ｋｇ（对照组）和氯胺酮１００ｍｇ／ｋｇ。用分光光度法测定ＮＯＳ活性和ＮＯ产量。结果：大鼠ｉｐ氯胺酮１００ｍｇ／ｋｇ能明显抑制小脑、大脑皮层、海马的ＮＯＳ活性和减少ＮＯ的产量（Ｐ＜００５或Ｐ＜００１），脑干的ＮＯ产量亦较对照组减少（Ｐ＜００１），ＮＯＳ活性下降，但无统计学意义。结论：大鼠ｉｐ氯胺酮１００ｍｇ／ｋｇ能明显抑制脑ＮＯＳ活性和减少ＮＯ产量，表明ＮＯ可能在氯胺酮全麻分子学机理中具有重要作用 Objective: To investigate the effects of ketamine on NOS activity and NO production in rat brain. Methods: Sixteen SD rats were randomly divided into two groups, ip saline 10ml / kg (control group) and ketamine 100mg / kg. NOS activity and NO production were determined spectrophotometrically. Results: Ketamine at 100 mg / kg significantly inhibited NOS activity and NO production (P <005 or P <001) in cerebellum, cerebral cortex and hippocampus, and NO production in brainstem (P <001), NOS activity decreased, but not statistically significant. CONCLUSION: 100 mg / kg ip ketamine significantly inhibits brain NOS activity and NO production, indicating that NO may play an important role in the molecular mechanism of ketamine anesthesia