Kinetic analysis of changes in activity of heart mitochondrial oxidative phosphorylation system induced by ischemia
Kinetic analysis of changes in activity of heart mitochondrial oxidative phosphorylation system induced by ischemia
复制标题
DOI：
10.1006/jmcc.1996.0211
复制
发表时间：
1996-10-01
影响因子：
5
通讯作者：
Brown, GC
中科院分区：
文献类型：
--
作者：
Borutaite, V;Morkuniene, R;Brown, GC
作者先前已经表明，缺血导致呼吸链和磷酸化系统的抑制，并刺激从大鼠心脏分离的线粒体的质子泄漏。它表明，在这里，线粒体呼吸链的活性（缺血30分钟后，但不是45分钟后）和磷酸化系统完全恢复到正常水平，通过添加外源性细胞色素c时，琥珀酸被用作底物。此外，细胞色素c引起呼吸链、磷酸化系统和正常线粒体中的质子泄漏的明显活化。这可以通过线粒体群体中缺乏细胞色素c的一部分来解释，并且该部分可以随着缺血而增加。对带皮心脏纤维的实验表明，缺血15分钟后，细胞色素c对线粒体呼吸没有影响，但当缺血时间延长至30分钟和45分钟时，细胞色素c对呼吸的刺激作用逐渐增强，表明细胞色素c的损失可能发生在体内。在缺血的早期可逆阶段。心肌缺血45分钟后分离的线粒体在呼吸链中有一个缺陷，与细胞色素c的丢失无关。这些线粒体具有增加的Ca 2+水平：10.05 nmol/mg蛋白质，与对照线粒体中的4.64 nmol/mg和30分钟缺血线粒体中的4.32 nmol/mg相比。缺血性线粒体中质子漏的增加大多数可被白蛋白逆转，因此可能与缺血性线粒体中游离脂肪酸水平增加有关。(C)1996年学术出版社
The authors have previously shown that ischemia causes inhibition of the respiratory chain and phosphorylation system, and stimulation of the proton leak of mitochondria isolated from rat heart. It is shown here that the activity of the mitochondrial respiratory chain (after 30 min ischemia, but not after 45 min) and the phosphorylation system are completely restored to the normal level by the addition of exogenous cytochrome c when succinate is used as substrate. Moreover, cytochrome c causes apparent activation of the respiratory chain, the phosphorylation system and the proton leak in normal mitochondria. This can be explained by a fraction of the mitochondrial population lacking cytochrome c and this fraction may increase with ischemia. Experiments on skinned cardiac fibers showed that cytochrome c has no effect on mitochondrial respiration after 15 min ischemia, but the stimulation of respiration by cytochrome c progressively increases when ischemia was prolonged up to 30 min and 45 min, suggesting that the loss of cytochrome c may occur in vivo during the early reversible phase of ischemia. Mitochondria isolated from hearts after 45 min ischemia have a defect in the respiratory chain unrelated to the loss, of cytochrome c. These mitochondria have an increased level of Ca2+: 10.05 nmol/mg protein compared to 4.64 nmol/mg in control mitochondria and 4.32 nmol/mg in 30 min ischemic mitochondria. The increase in the proton leak in ischemic mitochondria is mostly reversible by albumin and thus, may be related to an increased level of free fatty acids in ischemic mitochondria. (C) 1996 Academic Press Limited