The membrane potential (DeltaPsim) dependence of the generation of reactive oxygen species (ROS) in isolated guinea-pig brain mitochondria respiring on NADH-linked substrates (glutamate plus malate) was addressed. Depolarization by FCCP was without effect on H(2)O(2) formation in the absence of bovine serum albumin (BSA). Addition of BSA (0.025%) to the assay medium hyperpolarized mitochondria by 6.1 +/- 0.9 mV (from 169 +/- 3 to 175.1 +/- 2.1 mV) and increased the rate of H(2)O(2) formation from 207 +/- 4.5 to 312 +/- 12 pmol/min/mg protein. Depolarization by FCCP (5-250 nM) in the presence of BSA decreased H(2)O(2) formation but only to the level observed in the absence of BSA. Rotenone stimulated the formation of H(2)O(2) both in the absence and presence of BSA. It is suggested that H(2)O(2) formation in mitochondria supported by NADH-linked substrates is sensitive to changes in DeltaPsim only when mitochondria are highly polarized and even then, 60% of ROS generation is independent of DeltaPsim. This is in contrast to earlier reports on the highly DeltaPsim sensitive ROS formation related to reverse electron flow observed in well-coupled succinate-supported mitochondria.

译文

:解决了在NADH连接的底物(谷氨酸加苹果酸)上呼吸的分离的豚鼠脑线粒体中活性氧物质(ROS)生成的膜电位(DeltaPsim)依赖性。在没有牛血清白蛋白(BSA)的情况下,通过FCCP去极化对H(2)O(2)的形成没有影响。将BSA(0.025%)添加到测定介质超极化线粒体的6.1 /-0.9 mV(从169 /-3到175.1 /-2.1 mV),并将H(2)O(2)的形成速率从207 /-增加4.5至312 /-12 pmol / min / mg蛋白质。由存在于BSA的FCCP(5-250 nM)进行的去极化降低了H(2)O(2)的形成,但仅达到了在没有BSA的情况下所观察到的水平。鱼藤酮在没有和存在BSA的情况下刺激H(2)O(2)的形成。建议仅在线粒体高度极化并且即使那时,60%的ROS生成独立于DeltaPsim时,NADH链接的底物支持的线粒体中的H(2)O(2)形成对DeltaPsim的变化敏感。这与早先报道的关于高度DeltaPsim敏感的ROS形成相反,后者在良好耦合的琥珀酸负载的线粒体中观察到与反向电子流有关。

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