Xie Ying, Zhong Caigao, Zeng Ming, Guan Lan, Luo Lei
Department of Health Toxicology, School of Public Health, Central South University, Changsha, China.
Cell Physiol Biochem. 2013;31(2-3):473-85. doi: 10.1159/000350062. Epub 2013 Mar 20.
BACKGROUND/AIMS: In the present study, we explored reactive axygen species (ROS) production in mitochondria, the mechanism of hexavalent chromium (Cr(VI)) hepatotoxicity, and the role of protection by GSH.
Intact mitochondria were isolated from rat liver tissues and mitochondrial basal respiratory rates of NADH and FADH2 respiratory chains were determined. Mitochondria were treated with Cr(VI), GSH and several complex inhibitors. Mitochondria energized by glutamate/malate were separately or jointly treated with Rotenone (Rot), diphenyleneiodonium (DPI) and antimycinA (Ant), while mitochondria energized by succinate were separately or jointly treated with Rot, DPI ' thenoyltrifluoroacetone (TTFA) and Ant.
Cr(VI) concentration-dependently induced ROS production in the NADH and FADH2 respiratory chain in liver mitochondria. Basal respiratory rate of the mitochondrial FADH2 respiratory chain was significantly higher than that of NADH respiratory chain. Hepatic mitochondrial electron leakage induced by Cr(VI) from NADH respiratory chain were mainly from ubiquinone binding sites of complex I and complex III.
Treatment with 50µM Cr(VI) enhances forward movement of electrons through FADH2 respiratory chain and leaking through the ubiquinone binding site of complex III. Moreover, the protective effect of GSH on liver mitochondria electron leakage is through removing excess H2O2 and reducing total ROS.
背景/目的：在本研究中，我们探讨了线粒体中活性氧（ROS）的产生、六价铬（Cr(VI)）肝毒性的机制以及谷胱甘肽（GSH）的保护作用。
从大鼠肝脏组织中分离出完整的线粒体，测定NADH和FADH2呼吸链的线粒体基础呼吸速率。用Cr(VI)、GSH和几种复合抑制剂处理线粒体。用鱼藤酮（Rot）、二苯基碘鎓（DPI）和抗霉素A（Ant）分别或联合处理由谷氨酸/苹果酸供能的线粒体，而用Rot、DPI、噻吩甲酰三氟丙酮（TTFA）和Ant分别或联合处理由琥珀酸供能的线粒体。
Cr(VI)浓度依赖性地诱导肝线粒体中NADH和FADH2呼吸链产生ROS。线粒体FADH2呼吸链的基础呼吸速率显著高于NADH呼吸链。Cr(VI)诱导的肝线粒体NADH呼吸链电子泄漏主要来自复合物I和复合物III的泛醌结合位点。
用50µM Cr(VI)处理可增强电子通过FADH2呼吸链的正向移动，并通过复合物III的泛醌结合位点泄漏。此外，GSH对肝线粒体电子泄漏的保护作用是通过去除过量的H2O2和减少总ROS来实现的。
