Role of inorganic nitrite in methaemoglobin formation after nitrate ester administration to the rat.

1. Methaemoglobin is rapidly formed during the incubation of rat red cells with inorganic nitrite, whereas ethylene glycol dinitrate at a higher concentration has little effect.2. The concentrations of blood inorganic nitrite in the rat after ethylene glycol dinitrate or glyceryl trinitrate injection can be reproduced by the infusion of nitrite. The methaemoglobin formed after ethylene glycol dinitrate or glyceryl trinitrate injection is equivalent to that produced from nitrite infusions simulating its formation from the nitrate esters.3. It is concluded that methaemoglobin arising from nitrate ester administration is formed principally by the action of the metabolite inorganic nitrite.