Nitrite

About: Nitrite is a research topic. Over the lifetime, 15425 publications have been published within this topic receiving 484581 citations.

Nitrate and Nitrite in Health and Disease.

Abstract: The source of dietary nitrate (NO3) is mainly green, leafy vegetables, partially absorbed into blood through intestinal mucosa. The recycled nitrate is reabsorbed and concentrated by the salivary glands and then secreted into saliva. In 2012, sialin was first discovered as the mammalian membrane nitrate transporter in salivary glands and plays a key role in circulation of inorganic nitrate, providing a scientific basis for further investigation into the circulation and functions of nitrate. Dietary nitrate can be converted to nitrite (NO2) by oral commensal bacteria under the tongue or in the stomach, following which nitrite is converted to nitric oxide (NO) through non-enzymatic synthesis. Previously, nitrate and nitrite were thought to be carcinogenic due to the potential formation of nitrogen compounds, whereas the beneficial functions of NO3--NO2--NO pathway were ignored. Under conditions of hypoxia and ischemia, the production of endogenous NO from L-arginine is inhibited, while the activity of exogenous NO3--NO2--NO is enhanced. Recently, a greater amount of evidence has shown that nitrate and nitrite serve as a reservoir and perform positive biological NO-like functions. Therefore, exogenous dietary nitrate plays an important role in various physiological activities as an effective supplement of nitrite and NO in human body. Here we generally review the source, circulation and bio-functions of dietary nitrate.

Inhibition of methanogenesis in salt marsh sediments and whole-cell suspensions of methanogenic bacteria by nitrogen oxides.

Abstract: Hydrogen-dependent evolution of methane from salt marsh sediments and whole-cell suspensions of Methanobacterium thermoautotrophicum and Methanobacterium fornicicum ceased or decreased after the introduction of nitrate, nitrite, nitric oxide, or nitrous oxide. Sulfite had a similar effect on methanogenesis in the whole-cell suspensions. In salt marsh sediments, nitrous oxide was the strongest inhibitor, followed by nitric oxide, nitrite, and nitrate in decreasing order of inhibition. In whole-cell suspensions, nitric oxide was the strongest inhibitor, followed by nitrous oxide, nitrite, and nitrate. Consideration of the results from experiments using an indicator of oxidation potential, along with the reversed order of effectiveness of the nitrogen oxides in relation to their degree of reduction ,suggests that the inhibitory effect observed was not due to a redox change. Evidence is also presented that suggests that the decrease in the rate of methane production in the presence of oxides of nitrogen was not attributable to competition for methane-producing substrates.

Formation in vivo of volatile N -nitrosamines in man after ingestion of cooked bacon and spinach

Abstract: N-NITROSAMINES, which are thought to be causally related to human cancer1, have been found in μg kg−1 concentrations in polluted air2,3, in water4 and in tobacco products5. Foodstuffs such as cooked bacon, preserved with nitrite, have long been known to contain μg kg−1 amounts of volatile N-nitrosamines formed during cooking6. In vivo formation of N-nitrosamines, after ingestion of suitable amine precursors and nitrite, has been demonstrated in laboratory animals7. In vivo formation in human subjects with hypoacidity, gavaged with relatively massive amounts of diphenylamine plus nitrite, has been demonstrated through detection of N-nitrosodiphenylamine in the stomach contents8. In vivo nitrosation after ingestion of conventional foods has not been demonstrated so far, either in animals or man. We now report in vivo formation of volatile N-nitrosamines in man after ingestion of a midday meal consisting of a bacon, spinach and tomato sandwich and beer.