Jones Charles I, Han Zhaosheng, Presley Tennille, Varadharaj Saradhadevi, Zweier Jay L, Ilangovan Govindasamy, Alevriadou B Rita
Davis Heart and Lung Research Institute, Department of Internal Medicine, The Ohio State University, Columbus, OH 43210, USA.
Am J Physiol Cell Physiol. 2008 Jul;295(1):C180-91. doi: 10.1152/ajpcell.00549.2007. Epub 2008 May 14.
Cultured vascular endothelial cell (EC) exposure to steady laminar shear stress results in peroxynitrite (ONOO(-)) formation intramitochondrially and inactivation of the electron transport chain. We examined whether the "hyperoxic state" of 21% O(2), compared with more physiological O(2) tensions (Po(2)), increases the shear-induced nitric oxide (NO) synthesis and mitochondrial superoxide (O(2)(-)) generation leading to ONOO(-) formation and suppression of respiration. Electron paramagnetic resonance oximetry was used to measure O(2) consumption rates of bovine aortic ECs sheared (10 dyn/cm(2), 30 min) at 5%, 10%, or 21% O(2) or left static at 5% or 21% O(2). Respiration was inhibited to a greater extent when ECs were sheared at 21% O(2) than at lower Po(2) or left static at different Po(2). Flow in the presence of an endothelial NO synthase (eNOS) inhibitor or a ONOO(-) scavenger abolished the inhibitory effect. EC transfection with an adenovirus that expresses manganese superoxide dismutase in mitochondria, and not a control virus, blocked the inhibitory effect. Intracellular and mitochondrial O(2)(-) production was higher in ECs sheared at 21% than at 5% O(2), as determined by dihydroethidium and MitoSOX red fluorescence, respectively, and the latter was, at least in part, NO-dependent. Accumulation of NO metabolites in media of ECs sheared at 21% O(2) was modestly increased compared with ECs sheared at lower Po(2), suggesting that eNOS activity may be higher at 21% O(2). Hence, the hyperoxia of in vitro EC flow studies, via increased NO and mitochondrial O(2)(*-) production, leads to enhanced ONOO(-) formation intramitochondrially and suppression of respiration.
培养的血管内皮细胞（EC）暴露于稳定的层流切应力会导致线粒体内过氧亚硝酸盐（ONOO⁻）形成以及电子传递链失活。我们研究了与更接近生理状态的氧张力（Po₂）相比，21% O₂的“高氧状态”是否会增加剪切诱导的一氧化氮（NO）合成和线粒体超氧阴离子（O₂⁻*）生成，从而导致ONOO⁻形成并抑制呼吸作用。电子顺磁共振血氧测定法用于测量在5%、10%或21% O₂条件下剪切（10达因/平方厘米，30分钟）或在5%或21% O₂条件下静置的牛主动脉内皮细胞的耗氧率。与在较低Po₂条件下剪切或在不同Po₂条件下静置相比，当内皮细胞在21% O₂条件下剪切时，呼吸作用受到的抑制程度更大。在内皮型一氧化氮合酶（eNOS）抑制剂或ONOO⁻清除剂存在的情况下流动可消除这种抑制作用。用在线粒体内表达锰超氧化物歧化酶的腺病毒而非对照病毒转染内皮细胞可阻断这种抑制作用。分别通过二氢乙锭和MitoSOX红色荧光测定，在21% O₂条件下剪切的内皮细胞中细胞内和线粒体内O₂⁻*的产生高于在5% O₂条件下剪切的细胞，并且后者至少部分依赖于NO。与在较低Po₂条件下剪切的内皮细胞相比，在21% O₂条件下剪切的内皮细胞培养基中NO代谢产物的积累略有增加，这表明eNOS活性在21% O₂条件下可能更高。因此，体外内皮细胞流动研究中的高氧状态，通过增加NO和线粒体O₂⁻*的产生，导致线粒体内ONOO⁻形成增强和呼吸作用受到抑制。
