GENERATION OF NO DURING OXIDATION OF HEMOGLOBIN FERROFORMS BY NITRITE

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.