Studies on In Vivo Formation of Nitroso Compounds (IV)

Changes of Nitrite and Nitrate Concentration in Incubated Human Saliva

Abstract

When the human whole saliva containing 11.8ppm of nitrite and 65.0ppm of nitrate was incubated at 37°C for 1hr, these concentrations changed to 15.3 and 36.2ppm, respectively. Potassium ferricyanide-reducing substance in saliva was also determined, but no relation between the amounts of nitrite, nitrate and the reducing substance was found. In the saliva, either heated at 100°C for 10min or filtered with a membrane filter, any change of nitrite and nitrate contents was not observed during incubation at 37°C for 2hr. However, when the filtered saliva was supplemented with the residue on a filter, the changes of nitrite and nitrate concentration was restored to the level of the unfiltered saliva.
From these results, it might be concluded that bacteria in human mouth plays a main role in the reduction of nitrate.