Kim J H, Woldgiorgis G, Elson C E, Shrago E
Department of Nutritional Sciences, University of Wisconsin, Madison 53706.
Mech Ageing Dev. 1988 Dec;46(1-3):263-77. doi: 10.1016/0047-6374(88)90129-7.
Age-related changes affecting mitochondrial adenine nucleotide metabolism may underlie age-related decreases in hepatic metabolic activities. Oxidative activity coupled with phosphorylation, the apparent Km and Vmax of the adenine nucleotide translocase (AdNT), the adenine nucleotide pool size and membrane lipid composition were determined for hepatic mitochondria from young (3 months), mature (12 months) and aged (24 months) Fischer 344 male rats which had been fed NIH-31 diet. The age-related decreases in state 3 respiration supported by NAD-linked substrates were 2-4-fold greater than that of an FAD-linked substrate. The 32% (P less than 0.05) decrease in the AdNT Vmax calculated for the aged rats was accompanied by a 17% decrease in the AdNT Km. The exchangeable pool of adenine nucleotides in mitochondria from aged rats was 72% (P less than 0.05) that in the young rats. While the age-related increase in the cholesterol/phospholipid-Pi ratio and changes in the phospholipid head group pattern were not significant, the overall change in the fatty acid pattern effected a 20% (P less than 0.05) decrease in the n-6/n-3 fatty acid ratio. These data suggest that the reduced Vmax of the AdNT is a consequence of a diminished pool of exchangeable adenine nucleotides. The lower AdNT velocity may reflect the effect of changes in the lipid environment of the membrane in which it is embedded. The major shifts in these parameters occurred during the second year of life.
影响线粒体腺嘌呤核苷酸代谢的年龄相关变化可能是肝脏代谢活性随年龄下降的基础。测定了喂食NIH - 31饮食的年轻（3个月）、成熟（12个月）和老年（24个月）雄性Fischer 344大鼠肝脏线粒体的氧化磷酸化活性、腺嘌呤核苷酸转位酶（AdNT）的表观Km和Vmax、腺嘌呤核苷酸池大小以及膜脂质组成。由NAD连接底物支持的状态3呼吸随年龄的下降比FAD连接底物的下降大2至4倍。老年大鼠计算出的AdNT Vmax下降32%（P小于0.05），同时AdNT Km下降17%。老年大鼠线粒体中腺嘌呤核苷酸的可交换池是年轻大鼠的72%（P小于0.05）。虽然胆固醇/磷脂 - Pi比值随年龄的增加以及磷脂头部基团模式的变化不显著，但脂肪酸模式的总体变化使n - 6/n - 3脂肪酸比值下降了20%（P小于0.05）。这些数据表明，AdNT的Vmax降低是可交换腺嘌呤核苷酸池减少的结果。较低的AdNT速度可能反映了其嵌入的膜脂质环境变化的影响。这些参数的主要变化发生在生命的第二年。
