目的　探讨组织一氧化氮 (NO)含量与一氧化氮合酶 (NOS)活性的变化规律 ,揭示其与衰老的关系。方法　采用铜离子活化镉还原法、硫代巴比妥酸染色法和血红蛋白氧化法测定组织 NO、丙二醛 (MDA)含量和 NOS的活性。结果　与青年鼠组 (4～ 5月龄 )相比 ,老年鼠组 (2 0～ 2 2月龄 )心脑肾组织 NO降低差异显著性 (P<0 .0 1 ) ,而中年鼠组 (9～ 1 0月龄 )仅肾组织 NO含量降低有显著性差异 (P<0 .0 5)。与中年鼠组比较 ,老年鼠组仅在心脏组织 NO含量降低差异有显著性 (P<0 .0 1 )。中年鼠组心脑组织 NOS活性较青年鼠组降低 (P<0 .0 5) ;而老年鼠组组织 NOS活性较中年鼠组增高 ,仅脑组织 NOS增高有显著差异 (P<0 .0 5)。与青年鼠对照组比较 ,老年鼠组组织 NOS活性降低 ,但无显著性差异 (P>0 .0 5)。与青年鼠组比较 ,老年鼠组心肝脑肾组织 MDA增高 (P<0 .0 1 ) ,中年鼠组仅在肝组织有显著性 (P<0 .0 5)。老年鼠组心肝脑肾组织 MDA较中年鼠组增高 ,但仅在脑组织有显著性 (P<0 .0 5)。结论　 NO与衰老之间存在着一定的相关关系。 Objective To investigate the changes of nitric oxide (NO) content and nitric oxide synthase (NOS) activity in tissues and to reveal its relationship with aging. Methods The contents of NO, malondialdehyde (MDA) and activity of NOS were determined by Cu 2+ reduction with cadmium, thiobarbituric acid and hemoglobin oxidation. Results Compared with the young rats (4 ~ 5 months old), NO in the aged rats (20 ~ 22 months old) was significantly lower than that in the middle mice (P <0.01) (9 ~ 10 months old), there was a significant difference only in the reduction of NO content in kidney (P <0.05). Compared with the middle-aged rats, there was a significant difference in NO content in the aged rats only in the heart (P <0.01). The activity of NOS in heart and brain of middle-aged rats was lower than that of young rats (P <0.05), while the activity of NOS in aged rats was higher than that of middle-aged rats and increased only in NOS of brain tissues (P <0.05). 0 5). Compared with the control group of young rats, the activity of NOS in aged rats decreased but there was no significant difference (P> 0.05). Compared with the young rats, MDA in the heart, liver and kidney of the aged rats increased (P <0.01), but only in the liver tissues of the middle-aged rats (P <0.05). Compared with middle-aged rats, MDA in heart, liver and kidney of aged rats increased, but only in brain tissue (P <0.05). Conclusion There is a certain correlation between NO and aging.