Nitric oxide from inducible nitric oxide synthase sensitizes the inflamed aorta to hypoxic damage via respiratory inhibition.
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| Abstract |
We tested whether nitric oxide (NO) could synergize with hypoxia to induce damage to the aorta isolated from rat. We found that 4 h of mild hypoxia (5% O2) caused substantial necrosis of isolated rat aortae (measured as lactate dehydrogenase release) if inducible NO synthase (iNOS) had previously been induced by endotoxin plus interferon-gamma. Mild hypoxia caused no significant necrosis in the absence of this inflammatory activation, and inflammatory activation caused little damage at a higher oxygen levels (21% oxygen). An iNOS inhibitor (1400W) prevented the necrosis induced by inflammation plus mild hypoxia, whereas the NO donor diethylenetriamine (DETA)/NO adduct, 0.5 mM) greatly sensitized the noninflammed aorta to necrosis induced by mild hypoxia. NO inhibited aortic respiration to a greater degree at lower oxygen concentrations, consistent with NO inhibition of cytochrome oxidase in competition with oxygen. A specific inhibitor of mitochondrial respiration, myxothiazol, caused necrosis of aortae over a similar time course to NO. DETA/NO plus mild hypoxia-induced cell death was substantially reduced by a glycolytic intermediate 3-phosphoglycerate, suggesting that necrosis resulted from energy depletion secondary to respiratory inhibition. This NO-induced sensitization of aorta to mild hypoxia may be important in sepsis and other pathologies where iNOS is expressed.
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| Authors | Vilmante Borutaite, Salvador Moncada, Guy C Brown |
| Journal | Shock (Augusta, Ga.) (Shock) Vol. 23 Issue 4 Pg. 319-23 (Apr 2005) ISSN: 1073-2322 [Print] United States |
| PMID | 15803054 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't) |
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