The oxidation of hemoglobin solutions or erythrocyte suspensions conta
ining a mixture of deoxyHb and oxyHb by NaNO2 (under decreased partial
pressure of dissolved O-2) resulted in the generation of metHb and ni
trosoHb. The maximum amount of nitrosoHb was generated during the oxid
ation of deoxylHb. An increase in oxygen content was accompanied with
increased generation of metHb, which was the only hemoglobin form unde
r aerobic conditions. In the presence of oxygen, GSH was oxidized by N
aNO2 to GSSG either in solution of oxyHb or in the structure of erythr
ocytes. GSH decelerated the oxidation of Hb to metHb due to prolongati
on of the slow phase and suppression of the autocatalytic phase of the
reaction. The oxidation of GSH to GSSG was induced by (N) over dotO(2
) radicals and not by (N) over dotO. The incubation of deoxyHb with S-
nitrosoglutathione resulted in its complete conversion to nitrosoHb, a
nd this indicated that (N) over dotO was released during the spontaneo
us decomposition of GSNO. The addition of S-nitrosoglutathione to oxyH
b resulted in the generation of metHb in the solution.