Abstract
Summary
Monomethylhydrazine (MMH) was injected into rats, rabbits, and guinea pigs, and subsequent levels of methemoglobin in the blood were measured. Peak levels of methemoglobin occurred within an hour, but were less than 5% of blood hemoglobin with doses of MMH up to 0.54 mmoles/kg. In contrast, 5 to 8-fold higher levels have been previously observed in anesthetized dogs treated with comparable doses of MMH. In vitro incubations of MMH with blood from rats, rabbits, guinea pigs, dogs, and human subjects produced peak levels of methemoglobin within an hour. Peak levels were 4 to 8-fold higher when human or canine blood was incubated with MMH than when rat, rabbit, or guinea pig blood was similarly incubated. These results demonstrate that there is a marked difference among species in the levels of methemoglobin found either in vivo after MMH injection or in vitro during incubation of blood with MMH.
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