Lipoxygenase-dependent superoxide release in skeletal muscle.
Lipoxygenase-dependent superoxide release in skeletal muscle.
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骨骼肌中脂氧合酶依赖性超氧化物释放。
DOI：
10.1152/japplphysiol.00096.2004
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Clanton,ThomasL
中科院分区：
文献类型：
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作者：
Zuo,Li;Christofi,FievosL;Wright,ValerieP;Bao,Shengying;Clanton,ThomasL
超氧阴离子自由基（O2·−）在休息时从骨骼肌中释放出来，在热应激（42°C）条件下尤其升高。先前的研究表明，在离体大鼠膈肌中，O2·−的释放不依赖于线粒体电子传递、NADP氧化酶活性的降低或膜阴离子通道的完整性。这项研究假设O2·−释放（通过细胞色素还原测定）与花生四烯酸的代谢有关。抑制磷脂酶A2可显著降低O2·−释放。在下游通路中，用吲哚美辛阻断环加氧酶和用SKF-525 A抑制细胞色素P-450依赖性单加氧酶都不会减少O2·−的释放。然而，脂氧合酶（LOX）抑制剂5，8，11，14-二十碳四炔酸和肉桂基-3，4-二羟基-α-氰基肉桂酸大大减弱了信号。此外，特异性5-LOX抑制剂乙胺嗪也显著降低了O2·−的释放。免疫组化定位5-和12-LOX的肌细胞的胞浆和肌膜。使用O2·−敏感荧光指示剂氢乙啶的共聚焦研究表明，LOX抑制对细胞内O2·−形成没有显著影响。当与细胞色素结果比较时，这表明细胞内和细胞外O2·−必须来自不同的来源。这些数据首次表明，通过LOX活性的花生四烯酸代谢是骨骼肌细胞外O2·−释放的主要来源。
Superoxide anion radical (O2•−) is released from skeletal muscle at rest and is particularly elevated during conditions of heat stress (42°C). Previous studies have shown that in isolated rat diaphragm O2•−release is not dependent on mitochondrial electron transport, reduced NADP oxidase activity, or the integrity of membrane anion channels. This study hypothesized that O2•−release, as measured by cytochromecreduction, is linked to metabolism of arachidonic acid. Phospholipase A2inhibition with manoalide significantly decreased O2•−release. In downstream pathways, neither the blockage of cyclooxygenase with indomethacin nor the inhibition of cytochromeP-450-dependent monooxygenase with SKF-525A decreased O2•−release. However, lipoxygenase (LOX) inhibition with general LOX blockers 5,8,11,14-eicosatetraynoic acid and cinnamyl-3,4-dihydroxy-α-cyanocinnamate greatly attenuated the signal. Furthermore, the specific 5-LOX inhibitor diethylcarbamazine also significantly decreased O2•−release. Immunohistochemistry localized 5- and 12-LOX to the cytosol and sarcolemma of muscle cells. Confocal studies, using the O2•−-sensitive fluorescent indicator hydroethidine, demonstrated that LOX inhibition had no significant influence on intracellular O2•−formation. When compared with the cytochromecresults, this indicates that intra- and extracellular O2•−must arise from different sources. These data show for the first time that arachidonic acid metabolism through LOX activity, is a major source of extracellular O2•−release in skeletal muscle.