缺血预处理可保持线粒体膜电位并限制活性氧的产生。
Ischemic preconditioning preserves mitochondrial membrane potential and limits reactive oxygen species production.
机构信息
Division of Cardiothoracic Surgery, Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA.
出版信息
J Surg Res. 2012 Nov;178(1):8-17. doi: 10.1016/j.jss.2012.05.090. Epub 2012 Jun 17.
BACKGROUND
Mitochondrial superoxide radical (O(2)(•¯)) production increases after cardiac ischemia/reperfusion (IR). Ischemic preconditioning (IPC) preserves mitochondrial function and attenuates O(2)(•¯) production, but the mechanism is unknown. Mitochondrial membrane potential (mΔΨ) is known to affect O(2)(•¯) production; mitochondrial depolarization decreases O(2)(•¯) formation. We examined the relationship between O(2)(•¯) production and mΔΨ during IR and IPC.
MATERIALS/METHODS: Rat hearts were subjected to Control or IPC. Mitochondria were isolated at end equilibration (End EQ), end ischemia (End I), and end reperfusion (End RP). mΔΨ was measured using a tetraphenylphosphonium electrode. Mitochondrial O(2)(•¯) production was measured by electron paramagnetic resonance using DMPO spin trap. Cytochrome c levels were measured using high-pressure liquid chromatography.
RESULTS
IPC preserved mΔΨ at End I (-156 ± 5 versus -131 ± 6 mV, P < 0.001) and End RP (-168 ± 2 versus -155 ± 2 mV, P < 0.05). At End RP, IPC attenuated O(2)(•¯) production (2527 ± 221 versus 3523 ± 250 AU/mg protein, P < 0.05). IPC preserved cytochrome c levels (351 ± 14 versus 269 ± 16 picomoles/mg protein, P < 0.05) at End RP, and decreased mitochondrial cristae disruption (10% ± 4% versus 33% ± 7%, P < 0.05) and amorphous density formation (18% ± 4% versus 28% ± 1%, P < 0.05).
CONCLUSION
We conclude that IPC preserves mΔΨ, possibly by limiting disruption of mitochondrial inner membrane. IPC also decreases mitochondrial O(2)(•¯) production and preserves mitochondrial ultrastructure after IR. While it was previously held that slight decreases in mΔΨ decrease O(2)(•¯) production, our results indicate that preservation of mΔΨ is associated with decreased O(2)(•¯) and preservation of cardiac function in IPC. These findings indicate that the mechanism of IPC may not involve mΔΨ depolarization, but rather preservation of mitochondrial electrochemical potential.
背景
心脏缺血/再灌注（IR）后，线粒体超氧自由基（O(2)(•¯)）的产生增加。缺血预处理（IPC）可保护线粒体功能并减轻 O(2)(•¯)的产生，但机制尚不清楚。线粒体膜电位（mΔΨ）已知会影响 O(2)(•¯)的产生；线粒体去极化会减少 O(2)(•¯)的形成。我们在 IR 和 IPC 期间研究了 O(2)(•¯)的产生与 mΔΨ 之间的关系。
材料/方法：大鼠心脏接受对照或 IPC。在终末平衡（End EQ）、终末缺血（End I）和终末再灌注（End RP）时分离线粒体。使用四苯基膦电极测量 mΔΨ。使用 DMPO 自旋捕获通过电子顺磁共振测量线粒体 O(2)(•¯)的产生。使用高压液相色谱法测量细胞色素 c 水平。
结果
IPC 在 End I（-156 ± 5 对-131 ± 6 mV，P < 0.001）和 End RP（-168 ± 2 对-155 ± 2 mV，P < 0.05）时保存 mΔΨ。在 End RP 时，IPC 减弱了 O(2)(•¯)的产生（2527 ± 221 对 3523 ± 250 AU/mg 蛋白，P < 0.05）。IPC 在 End RP 时还保存了细胞色素 c 水平（351 ± 14 对 269 ± 16 皮摩尔/mg 蛋白，P < 0.05），并减少了线粒体嵴的破坏（10% ± 4%对 33% ± 7%，P < 0.05）和无定形密度形成（18% ± 4%对 28% ± 1%，P < 0.05）。
结论
我们的结论是，IPC 通过限制线粒体内膜的破坏来保存 mΔΨ。IPC 还减少了 IR 后线粒体 O(2)(•¯)的产生并保存了线粒体超微结构。尽管先前认为 mΔΨ 的轻微降低会减少 O(2)(•¯)的产生，但我们的结果表明，mΔΨ 的保存与 O(2)(•¯)的减少和 IPC 中心功能的保存有关。这些发现表明，IPC 的机制可能不涉及 mΔΨ 的去极化，而是保存线粒体电化学势能。
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