Isoflurane preconditioning uncouples mitochondria and protects against hypoxia-reoxygenation
Isoflurane preconditioning uncouples mitochondria and protects against hypoxia-reoxygenation
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DOI：
10.1152/ajpcell.00221.2006
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发表时间：
2007-05-01
影响因子：
5.5
通讯作者：
Bienengraeber, Martin
中科院分区：
文献类型：
--
作者：
Ljubkovic, Marko;Mio, Yasushi;Bienengraeber, Martin
在发生缺血再灌注之前，通过将心脏暴露于诸如挥发性麻醉剂之类的药物，可以显着减轻缺血性心脏损伤。这种预处理现象的一个标志是它的记忆，即使在去除预处理刺激后，心脏保护作用仍然持续存在。由于大量研究指出线粒体是预处理保护途径的关键参与者，因此本研究的目的是研究预处理剂异氟烷对线粒体生物能表型的影响。在完整的心肌细胞中应用异氟烷后，内源性黄素蛋白荧光（线粒体氧化还原状态的指标）升高至基线的 195 ± 16%，表明线粒体的氧化状态更高。异氟烷治疗还引起线粒体跨膜电位的部分耗散，即使在麻醉撤药后，线粒体跨膜电位仍保持去极化状态（在异氟烷暴露和冲洗期间，四甲基罗丹明荧光强度分别降至基线的 83 ± 3 和 81 ± 7%）。在从动物体内分离出的线粒体中也检测到了轻度解偶联，且 ATP 合成得以保留，揭示了其记忆本质。与来自未经预处理的动物的线粒体相比，这些线粒体在暴露于缺氧和复氧后，表现出更好的呼吸和 ATP 合成。部分线粒体去极化与异氟烷处理的线粒体中 Ca2+ 吸收的减少相平行，如当线粒体受到增加的 Ca2+ 挑战时 rhod-2 荧光增量减少所表明的那样（180 ± 24 对比对照组的 258 ± 14%）。总之，异氟烷预处理引起部分线粒体解偶联并减少线粒体 Ca2+ 摄取。这些作用可能会减少缺氧应激后线粒体损伤的程度。
Ischemic cardiac injury can be substantially alleviated by exposing the heart to pharmacological agents such as volatile anesthetics before occurrence of ischemia-reperfusion. A hallmark of this preconditioning phenomenon is its memory, when cardioprotective effects persist even after removal of preconditioning stimulus. Since numerous studies pinpoint mitochondria as crucial players in protective pathways of preconditioning, the aim of this study was to investigate the effects of preconditioning agent isoflurane on the mitochondrial bioenergetic phenotype. Endogenous flavoprotein fluorescence, an indicator of mitochondrial redox state, was elevated to 195 ± 16% of baseline upon isoflurane application in intact cardiomyocytes, indicating more oxidized state of mitochondria. Isoflurane treatment also elicited partial dissipation of mitochondrial transmembrane potential, which remained depolarized even after anesthetic withdrawal (tetramethylrhodamine fluorescence intensity declined to 83 ± 3 and 81 ± 7% of baseline during isoflurane exposure and washout, respectively). Mild uncoupling, with preserved ATP synthesis, was also detected in mitochondria that were isolated from animals that had been previously preconditioned by isoflurane in vivo, revealing its memory nature. These mitochondria, after exposure to hypoxia and reoxygenation, exhibited better preserved respiration and ATP synthesis compared with mitochondria from nonpreconditioned animals. Partial mitochondrial depolarization was paralleled by a diminished Ca2+uptake into isoflurane-treated mitochondria, as indicated by the reduced increment in rhod-2 fluorescence when mitochondria were challenged with increased Ca2+(180 ± 24 vs. 258 ± 14% for the control). In conclusion, isoflurane preconditioning elicits partial mitochondrial uncoupling and reduces mitochondrial Ca2+uptake. These effects are likely to reduce the extent of the mitochondrial damage after the hypoxic stress.