Venditti P, Masullo P, Di Meo S
Dipartimento di Fisiologia Generale ed Ambientale, Università di Napoli, Napoli, I-80134, Italy.
Arch Biochem Biophys. 1999 Dec 15;372(2):315-20. doi: 10.1006/abbi.1999.1494.
In this study, oxygen consumption and H(2)O(2) release rate by succinate or pyruvate/malate supplemented mitochondria isolated from skeletal muscle of trained and untrained rats were investigated. The overall mitochondrial antioxidant capacity and the effect of preincubation of mitochondria with GDP, an inhibitor of uncoupling proteins UCP1 and UCP2, on both succinate-supported H(2)O(2) release and membrane potential were also determined. The results indicate that training does not affect mitochondrial oxygen consumption with both complex-I- and complex II-linked substrates. Succinate-supported H(2)O(2) release was lower in trained than in untrained rats both in State 4 and State 3. Even the antimycin A-stimulated release was lower in trained rats. When pyruvate/malate were used as substrates, H(2)O(2) release rate was lower in trained rats only in the presence of antimycin A. The increase of mitochondrial protein content (determined by the ratio between cytochrome oxidase activities in homogenates and mitochondria) in trained muscle was such that the succinate-supported H(2)O(2) release per g of tissue was not significantly different in trained and untrained rats, while that supported by pyruvate/malate was higher in trained than in untrained animals. The lack of training-induced changes in overall antioxidant capacity of mitochondria indicates that the decrease in mitochondrial H(2)O(2) release cannot be attributed to a greater capacity of mitochondria to scavenge the reactive oxygen intermediates derived from univalent O(2) reduction by respiratory chain components. In contrast, the above decrease seems to depend on the drop induced by training in mitochondrial membrane potential. These training effects are not due to an increased level of mitochondrial uncoupling protein, because in the presence of GDP the increase in both membrane potential and H(2)O(2) release was greater in untrained than in trained rats.
在本研究中，对从训练有素和未训练大鼠的骨骼肌中分离出的、添加琥珀酸或丙酮酸/苹果酸的线粒体的氧气消耗和H₂O₂释放速率进行了研究。还测定了线粒体的整体抗氧化能力，以及用GDP（一种解偶联蛋白UCP1和UCP2的抑制剂）对线粒体进行预孵育对琥珀酸支持的H₂O₂释放和膜电位的影响。结果表明，训练不会影响线粒体利用与复合体I和复合体II相关的底物时的氧气消耗。在状态4和状态3下，训练有素的大鼠中琥珀酸支持的H₂O₂释放均低于未训练的大鼠。即使是抗霉素A刺激的释放，训练有素的大鼠中也较低。当使用丙酮酸/苹果酸作为底物时，只有在抗霉素A存在的情况下，训练有素的大鼠中的H₂O₂释放速率才较低。训练有素的肌肉中线粒体蛋白含量的增加（通过匀浆和线粒体中细胞色素氧化酶活性的比值来确定）使得每克组织中琥珀酸支持的H₂O₂释放在训练有素和未训练的大鼠中没有显著差异，而丙酮酸/苹果酸支持的H₂O₂释放在训练有素的大鼠中高于未训练的动物。训练未引起线粒体整体抗氧化能力的变化，这表明线粒体H₂O₂释放的减少不能归因于线粒体清除呼吸链成分单电子还原O₂产生的活性氧中间体的能力增强。相反，上述减少似乎取决于训练引起的线粒体膜电位下降。这些训练效果不是由于线粒体解偶联蛋白水平的增加，因为在GDP存在的情况下，未训练的大鼠中膜电位和H₂O₂释放的增加比训练有素的大鼠更大。
