[Formation of nitrites from nitrates in the digestive tract]

The authors performed in vitro incubations of gastrointestinal mucosae and contents in the rat, under anaerobiosis, in the presence of nitrates. Nitrate disappearance and nitrite appearance amounts were measured in the different incubation media. From these works it follows that a certain quantity of nitrates are actually reduced to nitrites specifically by the ileo-caecal microflora of rats and perhaps, to a lower degree, by the action of a nitrate-reductase which may occur in the digestive mucosae. Moreover, the authors carried out in situ perfusions into the small intestine of rats, by adding nitrates to the perfusion liquid at a concentration of 400 mg per litre. It was thus demonstrated that the nitrate-absorbing kinetics is very rapid but those nitrates do not gather in the blood; besides, the presence of nitrites in the perfusion medium indicates a possible nitrate reduction in the intestinal gut.