[Metabolism of nitrates-nitrites].

Once the pair nitrate-nitrite--in quantity respectively set by the ingestion level or transformation level by intestinal bacteria--has entered through the intestinal mucosa, it may react with active biochemical groups. Nitrite, owing to its high oxido-reduction potential, may induce the oxidation of a large number of compounds, as for example the Fe++ heme-Fe+++ hemine system, reduced cytochromes-oxidized cytochromes system, etc. If the presence of nitrite in blood is not clearly established, this is due to the nitrite high chemical reactivity. Moreover, a transformation by the tissues of nitrates into nitrites after a nitro-reduction is quite possible.