Division of Cardiology, Department of Medicine, Virginia Commonwealth University , Richmond, Virginia.
Division of Exercise Physiology, Mitochondria, Metabolism, and Bioenergetics Working Group, West Virginia University , Morgantown, West Virginia.
Am J Physiol Heart Circ Physiol. 2018 Apr 1;314(4):H787-H795. doi: 10.1152/ajpheart.00531.2017. Epub 2017 Dec 29.
Cardiac ischemia-reperfusion (I/R) damages the electron transport chain (ETC), causing mitochondrial and cardiomyocyte injury. Reversible blockade of the ETC at complex I during ischemia protects the ETC and decreases cardiac injury. In the present study, we used an unbiased proteomic approach to analyze the extent of ETC-driven mitochondrial injury during I/R. Isolated-perfused mouse (C57BL/6) hearts underwent 25-min global ischemia (37°C) and 30-min reperfusion. In treated hearts, amobarbital (2 mM) was given for 1 min before ischemia to rapidly and reversibly block the ETC at complex I. Mitochondria were isolated at the end of reperfusion and subjected to unbiased proteomic analysis using tryptic digestion followed by liquid chromatography-mass spectrometry with isotope tags for relative and absolute quantification. Amobarbital treatment decreased cardiac injury and protected respiration. I/R decreased the content ( P < 0.05) of multiple mitochondrial matrix enzymes involved in intermediary metabolism compared with the time control. The contents of several enzymes in fatty acid oxidation were decreased compared with the time control. Blockade of ETC during ischemia largely prevented the decreases. Thus, after I/R, not only the ETC but also multiple pathways of intermediary metabolism sustain damage initiated by the ETC. If these damaged mitochondria persist in the myocyte, they remain a potent stimulus for ongoing injury and the transition to cardiomyopathy during prolonged reperfusion. Modulation of ETC function during early reperfusion is a key strategy to preserve mitochondrial metabolism and to decrease persistent mitochondria-driven injury during longer periods of reperfusion that predispose to ventricular dysfunction and heart failure. NEW & NOTEWORTHY Ischemia-reperfusion (I/R) damages mitochondria, which could be protected by reversible blockade of the electron transport chain (ETC). Unbiased proteomics with isotope tags for relative and absolute quantification analyzed mitochondrial damage during I/R and found that multiple enzymes in the tricarboxylic acid cycle, fatty acid oxidation, and ETC decreased, which could be prevented by ETC blockade. Strategic ETC modulation can reduce mitochondrial damage and cardiac injury.
心肌缺血再灌注（I/R）损伤电子传递链（ETC），导致线粒体和心肌细胞损伤。在缺血期间可逆性地抑制复合物 I 处的 ETC 可保护 ETC 并减少心脏损伤。在本研究中，我们使用无偏倚的蛋白质组学方法来分析 I/R 期间 ETC 驱动的线粒体损伤的程度。分离灌注的小鼠（C57BL/6）心脏经历 25 分钟的整体缺血（37°C）和 30 分钟的再灌注。在治疗的心脏中，在缺血前给予安米巴比妥（2mM）1 分钟，以快速和可逆地抑制复合物 I 处的 ETC。在再灌注结束时分离线粒体，并使用胰蛋白酶消化进行无偏蛋白质组学分析，然后进行液相色谱-质谱联用和同位素标记相对和绝对定量。安米巴比妥处理可减少心脏损伤并保护呼吸作用。与时间对照相比，I/R 降低了多个参与中间代谢的线粒体基质酶的含量（P<0.05）。与时间对照相比，脂肪酸氧化中的几种酶的含量降低。在缺血期间阻断 ETC 可大大防止这些减少。因此，I/R 后，不仅 ETC，而且中间代谢的多个途径也会受到 ETC 引发的损伤。如果这些受损的线粒体在心肌细胞中持续存在，它们仍然是持续损伤和在延长的再灌注期间向心肌病转化的潜在有力刺激。在早期再灌注期间调节 ETC 功能是维持线粒体代谢和减少持续的线粒体驱动损伤的关键策略，这种损伤会在更长时间的再灌注期间导致心室功能障碍和心力衰竭。新的和值得注意的是，缺血再灌注（I/R）会损伤线粒体，而可逆性地阻断电子传递链（ETC）可以保护线粒体。使用同位素标记相对和绝对定量的无偏蛋白质组学分析了 I/R 期间的线粒体损伤，发现三羧酸循环、脂肪酸氧化和 ETC 中的多种酶减少，而 ETC 阻断可预防这些减少。策略性地调节 ETC 可以减少线粒体损伤和心脏损伤。
