Knowledge of the physiology of the nitrites is much confused. This may be attributed in part to the previous lack of a test sufficiently sensitive yet specific for detecting the presence of or measuring extremely minute quantities of nitrite. Very minute doses of nitrite have profound physiologic effects. Although an immense amount of investigation has yielded many significant observations, many enigmas still remain unsolved in this complex field.
Glyceryl trinitrate was discovered by Sobrero1 in 1847, and the first physiologic studies on nitrites were initiated. Since then the accumulated literature has become enormous, and only a few significant papers can be reviewed here. Early analytic studies2 revealed nitrite in many tissues but in some only after the tissues were ground. Liver reduces nitrate to nitrite.3 The mechanism of this reduction is not definitely determined, but a vital process is presumably involved because this reduction is completely abolished
STIEGLITZ EJ, PALMER AE. THE BLOOD NITRITE. Arch Intern Med (Chic). 1937;59(4):620-630. doi:10.1001/archinte.1937.00170200062005