Differential Inhibition of Electron Transport Chain Enzyme Complexes by Cadmium and Calcium in Isolated Rainbow Trout (Oncorhynchus mykiss) Hepatic Mitochondria
Differential Inhibition of Electron Transport Chain Enzyme Complexes by Cadmium and Calcium in Isolated Rainbow Trout (Oncorhynchus mykiss) Hepatic Mitochondria
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DOI：
10.1093/toxsci/kfs091
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发表时间：
2012-05-01
影响因子：
3.8
通讯作者：
Kamunde, Collins
中科院分区：
文献类型：
--
作者：
Adiele, Reginald C.;Stevens, Don;Kamunde, Collins
电子传递链（ETC）受损与镉（Cd）和钙（Ca）诱导的线粒体功能障碍有关。本地化的网站的损害，0-50亩M镉和钙，单独和组合，对复杂的I-IV驱动的呼吸的影响进行了研究，使用分离的虹鳟鱼肝线粒体。线粒体镉/钙积累和呼吸速率进行了测量后，顺序抑制和激活的复合物I，II，III和IV。线粒体三磷酸腺苷（ATP）的合成测定暴露于（微摩尔）20镉和50钙，单独和组合，而丙二醛（MDA）测定孵育0-1 μ M镉和/或钙。我们发现，线粒体积累的镉和钙和状态3和4呼吸速率依赖于活性ETC复合物。尽管复合物IV对Cd和/或Ca具有高度的抑制作用，但观察到复合物I、II和III驱动的状态3呼吸速率的剂量依赖性抑制，其中半最大抑制浓度（IC 50）为（微摩尔）分别为12.4、12和13.7（Cd）; 57.1、46.1和26.2（Ca）;以及8.3、13.5和5.1（Cd + Ca）。较低的IC 50值为复杂的I-和III-介导的呼吸在镉+钙治疗表明，这些复合物的镉和钙的合作行动的网站。状态4呼吸速率不受镉和/或钙暴露，但减少线粒体耦合是明显的，从较低的呼吸控制和腺苷二磷酸/O的比率，除了在线粒体氧化复合物IV基板。此外，有减少ATP合成的复合物I基板激励线粒体和增加MDA浓度的症状膜脂质过氧化。
Impairment of the electron transport chain (ETC) is implicated in cadmium (Cd)- and calcium (Ca)-induced mitochondrial dysfunction. To localize the sites of the impairment, effects of 0-50 mu M Cd and Ca, singly and in combination, on complex I- to IV-driven respirations were investigated using isolated rainbow trout liver mitochondria. Mitochondrial Cd/Ca accumulation and respiration rates were measured following sequential inhibition and activation of complexes I, II, III, and IV. Mitochondrial adenosine triphosphate (ATP) synthesis was measured on exposure to (micromolar) 20 Cd and 50 Ca, singly and combined, whereas malondialdehyde (MDA) was measured on incubation with 0-1 mu M Cd and/or Ca. We show that mitochondrial accumulation of Cd and Ca and the states 3 and 4 rates of respiration depended on the active ETC complex. Although complex IV was highly recalcitrant to Cd and/or Ca, dose-dependent inhibitions of complex I-, II-, and III-driven state 3 respiration rates were observed with half maximal inhibitory concentrations (IC50) of (micromolar) 12.4, 12, and 13.7 (Cd); 57.1, 46.1, and 26.2 (Ca); and 8.3, 13.5, and 5.1 (Cd + Ca), respectively. The lower IC50 values for complex I- and III-mediated respirations in the Cd + Ca treatment suggests that these complexes are the sites of cooperative actions of Cd and Ca. State 4 respiration rates were unaffected by Cd and/or Ca exposure but reduced mitochondrial coupling was apparent from the lower respiratory control and adenosine diphosphate/O ratios except in mitochondria oxidizing complex IV substrate. Additionally, there was reduced ATP synthesis in complex I substrates energized mitochondria and increased MDA concentrations symptomatic of membrane lipid peroxidation.