Control of adenine nucleotide metabolism in hepatic mitochondria from rats with ethanol-induced fatty liver.
Control of adenine nucleotide metabolism in hepatic mitochondria from rats with ethanol-induced fatty liver.
复制标题
乙醇诱导脂肪肝大鼠肝线粒体腺嘌呤核苷酸代谢的控制。
作者：
P. I. Spach;R. Bottenus;C. Cunningham
雄性大鼠在喂食含乙醇的饮食31天后发生脂肪肝。这些动物的肝线粒体催化ATP合成的速度较慢时，与配对喂养的对照组大鼠（对照线粒体）的线粒体相比，并表现出降低呼吸控制与琥珀酸作为底物，由于减少状态-3呼吸速率。在解偶联剂存在下，两组大鼠线粒体的呼吸相当。ATP和ADP的转运减少在线粒体从乙醇喂养的大鼠，与ADP摄取降低更显着的乙醇喂养。研究了乙醇喂养大鼠线粒体中影响腺嘌呤核苷酸易位的参数。进行的实验表明，降低腺嘌呤核苷酸易位在这些线粒体是不是由长链酰基辅酶A衍生物或未酯化的脂肪酸的易位酶的抑制的结果。内源性腺嘌呤核苷酸在这些线粒体的分析显示降低ATP浓度，但总腺嘌呤核苷酸没有减少。在实验中，这些线粒体中的内源性ATP转移到更高的浓度，通过与可氧化的底物或脱脂牛血清白蛋白孵育，ADP易位的速率增加，与内源性ATP浓度和ADP易位的速率之间观察到的线性相关性。乙醇喂养大鼠线粒体中ATP浓度降低表明ATP合成酶复合物以较慢的速率补充内源性ATP。降低ATP合成酶的ATP酶活性观察亚线粒体颗粒从乙醇喂养的动物表明合成酶复合物的功能下降。乙醇喂养大鼠线粒体中ATP合成速率的降低足以解释ADP转运和State-3呼吸的降低。
Male rats developed fatty liver after being fed on an ethanol-containing diet for 31 days. Liver mitochondria from these animals catalysed ATP synthesis at a slower rate when compared with mitochondria from pair-fed control rats (control mitochondria), and demonstrated lowered respiratory control with succinate as substrate, owing to a decrease in the State-3 respiratory rate. Respiration in the presence of uncoupler was comparable in mitochondria from both groups of rats. Translocation of both ATP and ADP was decreased in mitochondria from ethanol-fed rats, with ADP uptake being lowered more dramatically by ethanol feeding. Parameters influencing adenine nucleotide translocation were investigated in mitochondria from ethanol-fed rats. Experiments performed suggested that lowered adenine nucleotide translocation in these mitochondria is not the result of inhibition of the translocase by either long-chain acyl-CoA derivatives or unesterified fatty acids. Analysis of endogenous adenine nucleotides in these mitochondria revealed lowered ATP concentrations, but no decrease in total adenine nucleotides. In experiments where the endogenous ATP in these mitochondria was shifted to higher concentrations by incubation with oxidizable substrates or defatted bovine serum albumin, the rate of ADP translocation was increased, with a linear correlation being observed between endogenous ATP concentrations and the rate of ADP translocation. The depressed ATP concentration in mitochondria from ethanol-fed rats suggests that the ATP synthetase complex is replenishing endogenous ATP at a slower rate. The lowered ATPase activity of the ATP synthetase observed in submitochondrial particles from ethanol-fed animals suggests a decrease in the function of the synthetase complex. A decrease in the rate of ATP synthesis in mitochondria from ethanol-fed rats is sufficient to explain the decreased ADP translocation and State-3 respiration.