Department of Anesthesiology and Perioperative Medicine, Suzhou, China.
Institute of Clinical Medicine Research, Suzhou Hospital (West District) Affiliated to Nanjing Medical University, Suzhou Science and Technology Town Hospital, Suzhou, China.
Cardiorenal Med. 2018;8(2):113-122. doi: 10.1159/000485936. Epub 2018 Feb 1.
Anesthetic preconditioning (APC) of the myocardium is mediated in part by reversible alteration of mitochondrial function. Nitric oxide (NO) inhibits mitochondrial respiration and may mediate APC-induced cardioprotection. In this study, the effects of isoflurane on different states of mitochondrial respiration during the oxidation of complex I-linked substrates and the role of NO were investigated.
Mitochondria were isolated from Sprague-Dawley rat hearts. Respiration rates were measured polarographically at 28ºC with a computer-controlled Clark-type O2 electrode in the mitochondria (0.5 mg/mL) with complex I substrates glutamate/malate (5 mM). Isoflurane (0.25 mM) was administered before or after adenosine diphosphate (ADP)-initiated state 3 respiration. The NO synthase (NOS) inhibitor L-N5-(1-iminoethyl)-ornithine (L-NIO, 10 μM) and the NO donor S-nitroso-N-acetylpenicillamine (SNAP, 1 μM) were added before or after the addition of ADP.
Isoflurane administered in state 2 increased state 2 respiration and decreased state 3 respiration. This attenuation of state 3 respiration by isoflurane was similar when it was given during state 3. L-NIO did not alter mitochondrial respiration or the effect of isoflurane. SNAP only, added in state 3, decreased state 3 respiration and enhanced the isoflurane-induced attenuation of state 3 respiration.
Isoflurane has clearly distinguishable effects on different states of mitochondrial respiration during the oxidation of complex I substrates. The uncoupling effect during state 2 respiration and the attenuation of state 3 respiration may contribute to the mechanism of APC-induced cardioprotection. These effects of isoflurane do not depend on endogenous mitochondrial NO, as the NOS inhibitor L-NIO did not alter the effects of isoflurane on mitochondrial respiration.
心肌的麻醉预处理（APC）部分是通过线粒体功能的可逆改变来介导的。一氧化氮（NO）抑制线粒体呼吸，可能介导 APC 诱导的心脏保护作用。在这项研究中，研究了异氟醚对复合物 I 连接的底物氧化过程中不同线粒体呼吸状态的影响，以及 NO 的作用。
从 Sprague-Dawley 大鼠心脏中分离出线粒体。在 28°C 下，使用计算机控制的Clark 型 O2 电极在线粒体（0.5mg/mL）中测量含有复合物 I 底物谷氨酸/苹果酸（5mM）的线粒体呼吸速率。在 ADP 引发的状态 3 呼吸之前或之后，给予异氟醚（0.25mM）。在添加 ADP 之前或之后，加入一氧化氮合酶（NOS）抑制剂 L-N5-（1-亚氨基乙基）-鸟氨酸（L-NIO，10μM）和一氧化氮供体 S-亚硝基-N-乙酰青霉胺（SNAP，1μM）。
在状态 2 下给予异氟醚可增加状态 2 呼吸并降低状态 3 呼吸。异氟醚对状态 3 呼吸的这种抑制作用在状态 3 时给予时是相似的。L-NIO 不改变线粒体呼吸或异氟醚的作用。仅在状态 3 下添加的 SNAP 降低了状态 3 呼吸，并增强了异氟醚诱导的状态 3 呼吸抑制作用。
异氟醚对复合物 I 底物氧化过程中不同状态的线粒体呼吸有明显的可区分作用。在状态 2 呼吸时的解偶联作用和状态 3 呼吸的衰减可能是 APC 诱导的心脏保护作用的机制。异氟醚的这些作用不依赖于内源性线粒体 NO，因为 NOS 抑制剂 L-NIO 并未改变异氟醚对线粒体呼吸的作用。
