Sipos Ildiko, Tretter Laszlo, Adam-Vizi Vera
Neurochemical Group of MTA-SOTE EKSZ, Budapest, Hungary.
Neurochem Res. 2003 Oct;28(10):1575-81. doi: 10.1023/a:1025634728227.
Dependence on mitochondrial membrane potential (deltapsim) of hydrogen peroxide formation of in situ mitochondria in response to inhibition of complex I or III was studied in synaptosomes. Blockage of electron flow through complex I by rotenone or that through complex III by antimycin resulted in an increase in the rate of H2O2 generation as measured with the Amplex red assay. Membrane potential of mitochondria was dissipated by either FCCP (250 nM) or DNP (50 microM) and then the rate of H2O2 production was followed. Neither of the uncouplers had a significant effect on the rate of H2O2 production induced by rotenone or antimycin. Inhibition of the F0F1-ATPase by oligomycin, which also eliminates deltapsim in the presence of rotenone and antimycin, respectively, was also without effect on the ROS formation induced by rotenone and only slightly reduced the antimycin-induced H2O2 production. These results indicate that ROS generation of in situ mitochondria in nerve terminals in response to inhibition of complex I or complex III is independent of deltapsim. In addition, we detected a significant antimycin-induced H2O2 production when the flow of electrons through complex I was inhibited by rotenone, indicating that the respiratory chain of in situ mitochondria in synaptosomes has a substantial electron influx distal from the rotenone site, which could contribute to ROS generation when the complex III is inhibited.
在突触体中研究了原位线粒体过氧化氢生成对复合体I或III抑制的线粒体膜电位（Δψm）依赖性。鱼藤酮阻断通过复合体I的电子流或抗霉素阻断通过复合体III的电子流，导致用Amplex red检测法测得的H2O2生成速率增加。用FCCP（250 nM）或DNP（50 μM）耗散线粒体的膜电位，然后跟踪H2O2的产生速率。两种解偶联剂对鱼藤酮或抗霉素诱导的H2O2产生速率均无显著影响。寡霉素抑制F0F1 - ATP酶，在鱼藤酮和抗霉素存在时也分别消除Δψm，对鱼藤酮诱导的ROS形成也无影响，仅略微降低抗霉素诱导的H2O2产生。这些结果表明，神经末梢原位线粒体对复合体I或复合体III抑制的ROS生成与Δψm无关。此外，当鱼藤酮抑制通过复合体I的电子流时，我们检测到抗霉素诱导的显著H2O2产生，表明突触体中原位线粒体的呼吸链在鱼藤酮位点远端有大量电子流入，当复合体III被抑制时这可能有助于ROS生成。
