The formation of methemoglobin by the action of nitrite on bovine blood.

Reactions of nitrite with hemoglobin in cattle blood under conditions of oxygen saturation and under conditions of oxygen exclusion are described.Each mole of oxyhemoglobin monomer reacts with 1 mol of nitrite resulting in the formation of 1 mol of methemoglobin and 1 mol of nitrate.Each mole of hemoglobin monomer reacts with 1 mol of nitrite producing a relatively stable HbNO compound.HbNO decomposes during the normal methem oglobin analysis, leading to the formation of 2 mol of methemoglobin and 1 mol of nitrate.Under in vivo conditions both reactions occur simultaneously.As a consequence a simple stoichiometric equation of the reaction of nitrite on blood cannot be given.In addition the results obtained with the widely used Evelyn and Malloy method of methemoglobin analysis deviate from the methemoglobin content as measured in whole blood.An estimation of the extent of the analytical differences is given.