亚硝酸盐
一氧化氮
化学
新陈代谢
生物化学
氧气
亚硝酸盐还原酶
细胞色素
硝酸盐
神经红蛋白
血红蛋白
酶
有机化学
珠蛋白
作者
Erin Curtis,Lewis L. Hsu,Audrey Noguchi,Lisa Geary,Sruti Shiva
标识
DOI:10.1089/ars.2011.4242
摘要
Aims: Once dismissed as an inert byproduct of nitric oxide (NO) auto-oxidation, nitrite (NO2-) is now accepted as an endocrine reservoir of NO that elicits biological responses in major organs. While it is known that tissue nitrite is derived from NO oxidation and the diet, little is known about how nitrite is metabolized by tissue, particularly at intermediate oxygen tensions. We investigated the rates and mechanisms of tissue nitrite metabolism over a range of oxygen concentrations. Results: We show that the rate of nitrite consumption differs in each organ. Further, oxygen regulates the rate and products of nitrite metabolism. In anoxia, nitrite is reduced to NO, with significant formation of iron–nitrosyl proteins and S-nitrosothiols. This hypoxic nitrite metabolism is mediated by different nitrite reductases in each tissue. In contrast, low concentrations (∼3.5 μM) of oxygen increase the rate of nitrite consumption by shifting nitrite metabolism to oxidative pathways, yielding nitrate. While cytochrome P450 and myoglobin contribute in the liver and heart, respectively, mitochondrial cytochrome c oxidase plays a significant role in nitrite oxidation, which is inhibited by cyanide. Using cyanide to prevent artifactual nitrite decay, we measure metabolism of oral and intraperitoneally administered nitrite in mice. Innovation: These data provide insight into the fate of nitrite in tissue, the enzymes involved in nitrite metabolism, and the role of oxygen in regulating these processes. Conclusion: We demonstrate that even at low concentrations, oxygen is a potent regulator of the rate and products of tissue nitrite metabolism. Antioxid. Redox Signal. 17, 951–961.
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