In this study, we have characterized the cellular source and mechanism for the enhanced generation of reactive oxygen species (ROS) in the myocardium during Trypanosoma cruzi infection. Cardiac mitochondria of infected mice, as compared to normal controls, exhibited 63.3% and 30.8% increase in ROS-specific fluorescence of dihydroethidium (detects O(2) (*-)) and amplex red (detects H(2)O(2)), respectively. This increase in ROS level in cardiac mitochondria of infected mice was associated with a 59% and 114% increase in the rate of glutamate/malate- (complex I substrates) and succinate- (complex II substrate) supported ROS release, respectively, and up to a 74.9% increase in the rate of electron leakage from the respiratory chain when compared to normal controls. Inhibition studies with normal cardiac mitochondria showed that rotenone induced ROS generation at the Q(Nf)-ubisemiquinone site in complex I. In complex III, myxothiazol induced ROS generation from a site located at the Q(o) center that was different from the Q(i) center of O(2) (*-) generation by antimycin. In cardiac mitochondria of infected mice, the rate of electron leakage at complex I during forward (complex I-to-complex III) and reverse (complex II-to-complex I) electron flow was not enhanced, and complex I was not the main site of increased ROS production in infected myocardium. Instead, defects of complex III proximal to the Q(o) site resulted in enhanced electron leakage and ROS formation in cardiac mitochondria of infected mice. Treatment of infected mice with phenyl-alpha-tert-butyl-nitrone (PBN) improved the respiratory chain function, and, subsequently, decreased the extent of electron leakage and ROS release. In conclusion, we show that impairment of the Q(o) site of complex III resulted in increased electron leakage and O(2) (*-) formation in infected myocardium, and was controlled by PBN.

中文翻译：

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克氏锥虫感染小鼠心肌中复合体 III 的 Q(o) 位点处活性氧的线粒体生成得到增强：抗氧化剂的有益作用。

在这项研究中，我们描述了克氏锥虫感染期间心肌中活性氧 (ROS) 生成增强的细胞来源和机制。与正常对照相比，受感染小鼠的心脏线粒体在二氢乙锭（检测 O(2) (*-)）和 amplex red（检测 H(2)O(2)）的 ROS 特异性荧光方面表现出 63.3% 和 30.8% 的增加）， 分别。受感染小鼠心脏线粒体中 ROS 水平的这种增加与谷氨酸/苹果酸（复合物 I 底物）和琥珀酸（复合物 II 底物）支持 ROS 释放的速率分别增加 59% 和 114% 相关，并且与正常对照相比，呼吸链的电子泄漏率增加了 74.9%。对正常心脏线粒体的抑制研究表明，鱼藤酮诱导复合物 I 中 Q(Nf)-泛半醌位点的 ROS 生成。 (i) 抗霉素产生 O(2) (*-) 的中心。在受感染小鼠的心脏线粒体中，在正向（复合物 I 到复合物 III）和反向（复合物 II 到复合物 I）电子流过程中复合物 I 的电子泄漏率没有增强，复合物 I 不是主要的受感染心肌中 ROS 产生增加的部位。相反，Q(o) 位点附近的复杂 III 的缺陷导致受感染小鼠心脏线粒体中的电子泄漏和 ROS 形成增强。用苯基-α-叔丁基-硝酮 (PBN) 治疗受感染的小鼠可改善呼吸链功能，并随后降低电子泄漏和 ROS 释放的程度。总之，我们表明复杂 III 的 Q(o) 位点的损伤导致受感染心肌中的电子泄漏增加和 O(2) (*-) 形成，并且受 PBN 控制。