Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
Anesthesiology. 2011 Sep;115(3):531-40. doi: 10.1097/ALN.0b013e31822a2316.
Reactive oxygen species (ROS) mediate the effects of anesthetic precondition to protect against ischemia and reperfusion injury, but the mechanisms of ROS generation remain unclear. In this study, the authors investigated if mitochondria-targeted antioxidant (mitotempol) abolishes the cardioprotective effects of anesthetic preconditioning. Further, the authors investigated the mechanism by which isoflurane alters ROS generation in isolated mitochondria and submitochondrial particles.
Rats were pretreated with 0.9% saline, 3.0 mg/kg mitotempol in the absence or presence of 30 min exposure to isoflurane. Myocardial infarction was induced by left anterior descending artery occlusion for 30 min followed by reperfusion for 2 h and infarct size measurements. Mitochondrial ROS production was determined spectrofluorometrically. The effect of isoflurane on enzymatic activity of mitochondrial respiratory complexes was also determined.
Isoflurane reduced myocardial infarct size (40 ± 9% = mean ± SD) compared with control experiments (60 ± 4%). Mitotempol abolished the cardioprotective effects of anesthetic preconditioning (60 ± 9%). Isoflurane enhanced ROS generation in submitochondrial particles with nicotinamide adenine dinucleotide (reduced form), but not with succinate, as substrate. In intact mitochondria, isoflurane enhanced ROS production in the presence of rotenone, antimycin A, or ubiquinone when pyruvate and malate were substrates, but isoflurane attenuated ROS production when succinate was substrate. Mitochondrial respiratory experiments and electron transport chain complex assays revealed that isoflurane inhibited only complex I activity.
The results demonstrated that isoflurane produces ROS at complex I and III of the respiratory chain via the attenuation of complex I activity. The action on complex I decreases unfavorable reverse electron flow and ROS release in myocardium during reperfusion.
活性氧（ROS）介导麻醉预处理的作用，以防止缺血再灌注损伤，但 ROS 生成的机制尚不清楚。在这项研究中，作者研究了线粒体靶向抗氧化剂（mitotempol）是否会消除麻醉预处理的心脏保护作用。此外，作者还研究了异氟醚改变分离线粒体和亚线粒体颗粒中 ROS 生成的机制。
大鼠用 0.9%生理盐水预处理，或在不存在或存在 30 分钟暴露于异氟醚的情况下用 3.0mg/kg mitotempol 预处理。通过左前降支闭塞 30 分钟诱导心肌梗死，然后再灌注 2 小时，并测量梗死面积。通过荧光光谱法测定线粒体 ROS 生成。还测定了异氟醚对线粒体呼吸复合物酶活性的影响。
异氟醚降低了心肌梗死面积（40±9%=平均值±标准差），与对照实验（60±4%）相比。mitotempol 消除了麻醉预处理的心脏保护作用（60±9%）。异氟醚以烟酰胺腺嘌呤二核苷酸（还原型）为底物增强了亚线粒体颗粒中的 ROS 生成，但以琥珀酸为底物时则不增强。在完整的线粒体中，当丙酮酸和苹果酸为底物时，异氟醚在加入鱼藤酮、抗霉素 A 或泛醌时增强 ROS 生成，但当琥珀酸为底物时，异氟醚减弱 ROS 生成。线粒体呼吸实验和电子传递链复合物测定表明，异氟醚仅抑制复合物 I 的活性。
结果表明，异氟醚通过抑制复合物 I 的活性在呼吸链的复合物 I 和 III 中产生 ROS。在再灌注期间，复合物 I 的作用降低了不利的反向电子流和心肌中 ROS 的释放。
