Madungwe Ngonidzashe B, Zilberstein Netanel F, Feng Yansheng, Bopassa Jean C
Department of Physiology, School of Medicine, University of Texas Health Science Center at San AntonioTX, USA; Department of Biomedical Engineering, University of Texas at San AntonioTX, USA.
Sackler School of Medicine, Tel Aviv University Israel.
Am J Cardiovasc Dis. 2016 Sep 15;6(3):93-108. eCollection 2016.
Reactive oxygen species (ROS) generation has been implicated in many pathologies including ischemia/reperfusion (I/R) injury. This led to multiple studies on antioxidant therapies to treat cardiovascular diseases but paradoxically, results have so far been mixed as ROS production can be beneficial as a signaling mechanism and in cardiac protection via preconditioning interventions. We investigated whether the differential impact of increased ROS in injury as well as in protection could be explained by their site of production on the mitochondrial electron transport chain. Using amplex red to measure ROS production, we found that mitochondria isolated from hearts after I/R produced more ROS than non-ischemic when complex I substrate (glutamate/malate) was used. Interestingly, the substrates of complex II (succinate) and ubiquinone (sn-glycerol 3-phosphate, G3P) produced less ROS in mitochondria from I/R hearts compared to normal healthy hearts. The inhibitors of complex I (rotenone) and complex III (antimycin A) increased ROS production when glutamate/malate and G3P were used; in contrast, they reduced ROS production when the complex II substrate was used. Mitochondrial calcium retention capacity required to induce mitochondrial permeability transition pore (mPTP) opening was measured using calcium green fluorescence and was found to be higher when mitochondria were treated with G3P and succinate compared to glutamate/malate. Furthermore, Langendorff hearts treated with glutamate/malate exhibited reduced cardiac functional recovery and increased myocardial infarct size compared to hearts treated with G3P. Thus, ROS production by the stimulated respiratory chain complexes I and III has opposite roles: cardio-deleterious when produced in complex I and cardio-protective when produced in complex III. The mechanism of these ROS involves the inhibition of the mPTP opening, a key event in cell death following ischemia/reperfusion injury.
活性氧（ROS）的产生与包括缺血/再灌注（I/R）损伤在内的多种病理过程有关。这引发了多项关于抗氧化疗法治疗心血管疾病的研究，但矛盾的是，目前的结果喜忧参半，因为ROS的产生作为一种信号机制以及通过预处理干预在心脏保护中可能是有益的。我们研究了ROS增加在损伤和保护方面的不同影响是否可以通过其在线粒体电子传递链上的产生部位来解释。使用安吖啶红来测量ROS的产生，我们发现当使用复合体I底物（谷氨酸/苹果酸）时，I/R后从心脏分离的线粒体产生的ROS比非缺血线粒体更多。有趣的是，与正常健康心脏相比，复合体II底物（琥珀酸）和泛醌（sn-甘油3-磷酸，G3P）在I/R心脏的线粒体中产生的ROS更少。当使用谷氨酸/苹果酸和G3P时，复合体I抑制剂（鱼藤酮）和复合体III抑制剂（抗霉素A）增加了ROS的产生；相反，当使用复合体II底物时，它们减少了ROS的产生。使用钙绿荧光测量诱导线粒体通透性转换孔（mPTP）开放所需的线粒体钙保留能力，发现与谷氨酸/苹果酸相比，用G3P和琥珀酸处理线粒体时该能力更高。此外，与用G3P处理的心脏相比，用谷氨酸/苹果酸处理的Langendorff心脏表现出心脏功能恢复降低和心肌梗死面积增加。因此，受刺激的呼吸链复合体I和III产生的ROS具有相反的作用：在复合体I中产生时对心脏有害，在复合体III中产生时对心脏有保护作用。这些ROS的机制涉及抑制mPTP开放，这是缺血/再灌注损伤后细胞死亡的关键事件。
