The role of methemoglobin in acute butyl nitrite toxicity in mice.

When mice were exposed to butyl nitrites in an inhalation chamber, a significant level of methemoglobinemia is produced. The potency order for methemoglobin production of the four butyl nitrites (n-, iso-, sec-, tert-) is the same as that of their lethal concentrations (LC50 values) and parallels the ability of the agents to cause methemoglobin formation in mouse erythrocytes in vitro. Pretreatment with a single dose of methylene blue prevents the methemoglobin formation and protects against the lethality of the butyl nitrites.