衰老大鼠肝线粒体质与量的改变

目的：探究大鼠衰老时肝组织细胞线粒体的变化规律。方法：分别从４月龄和２４月龄大鼠的肝组织分离出线粒体，并用双缩脲法测定单位组织的线粒体蛋白；用Ｃｌａｒｋ氧电极极谱法分别测定线粒体呼吸链３个氧化酶活性：ＮＡＤＨ氧化酶、琥珀酸氧化酶和细胞色素氧化酶；用差光谱法（连二亚硫酸还原的消光值减去正铁氰化钾氧化的消光值）获得细胞色素ａ，ｂ，ｃ和ｃ１（Ｃｙｔａ，ｂ，ｃ和ｃ１）含量。结果：与４月龄大鼠相比，２４月龄大鼠的肝组织细胞线粒体含量有一定的下降，而３个氧化酶活性显著增强，同时细胞色素含量尤其是Ｃｙｔｂ和ｃ１也显著升高。结论：衰老大鼠肝组织线粒体呼吸链氧化功能增强可能是通过某种反馈机制使残存尚好的线粒体代偿性功能增强。

Changes of liver mitochondria in quantity and quality from aged rat

Objective: To study the changes of mitochondria isolated from the liver of aged rats. Methods: The liver mitochondria were isolated from rats aged 4 months(young group) and 24 months (senescent group) respectively by differential centrifugation; the mitochondrial population in rat hepatic cell was obtained quantitatively from measurement of mitochondrial protein by a biuret method; NADH oxidase (NADHOX), succinate oxidase (SUCOX), and cytochrome oxidase (CYTOX) activities were measured polarographically with Clark oxygen electrode; the content of cytochrome a, b, c, and c 1 (Cyt a,b,c and c 1)was evaluated by the differential spectra (dithionite reduced minus ferricyanide oxidized). Results: In comparison with the young group, there was a decline in mitochondrial population in aged rats; the activities of three oxidases , however, were significantly increased, and the content of cytochromes, especially cyt b, c 1, markedly increased. Conclusion: The enhancement of respiratory enzymatic activities of the liver mitonchondria from aged rats appears to be some compensatory mechanism by which workload of the remaining intact population of mitochondria is increased.