Abstract
Recent evidence indicates that nitrite and unsubstituted hydroxylamine are not toxicologically equivalent forms in vivo. Hydroxylamine has effects on red cell metabolism which are not shared by nitrite. Hydroxylamine has a greater tendency to generate sulfhemoglobin-like pigments and Heinz bodies in the red cells of certain mammalian species than do equal concentrations of nitrite. It is not clear whether sulfhemoglobin and Heinz body formation are due to the metabolic effects of hydroxylamine or to some fundamental difference between it and nitrite in the mechanisms of their reactions with hemoglobin. Heinz body formation by certain aberrant hemoglobins with amino acid substitutions appears to be triggered by a dissociation of the heme group from the globin moiety. When nitrite, hydroxylamine and ferricyanide were tested for their ability to elicit specific heme loss, only ferricyanide had a statistically significant effect, but all three reagents produced a loss of total hemoglobin relative to control preparations of oxyhemoglobin. Ferricyanide and hydroxylamine convert deoxyhemoglobin to methemoglobin, but deoxyhemoglobin is resistant to nitrite. Hydroxylamine converts some oxyhemoglobin to methemoglobin but sulfhemoglobin-like pigments are also formed. Some evidence suggests that the heme oxygen is released in the hydroxylamine-oxyhemoglobin reaction, but that this effect is masked by the contemporaneous oxidative decomposition of hydroxylamine.
Footnotes
- Received October 12, 1970.
- Accepted January 14, 1971.
- © 1971 by The Williams & Wilkins Co.
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