title: Conversion of endogenous cobalamins into microbiologically-inactive cobalamin analogues in rats by exposure to nitrous oxide.
abstract: Rats were exposed to a mixture of oxygen and nitrous oxide (1/1) for up to 18 d. There was a marked fall in both the serum and liver cobalamin levels. There was a significant rise in the concentration of microbiologically-inactive cobalamins in serum 24 h after exposure to N2O. The proportion of microbiologically-inactive cobalamin in liver increased throughout the period of exposure. We were unable to show a similar effect in sera from patients inhaling N2O for 24 h, nor by exposing rat plasma to N2O for 24 h. It was concluded that microbiologically-inactive cobalamins are produced in vivo from endogenous cobalamins and that one form appears to be a product of cobalamin oxidation.
mesh_terms: D000818:Animals; D001681:Biological Assay; D002352:Carrier Proteins / Q000378:metabolism; D006801:Humans; D008099:Liver / Q000378:metabolism; D008297:Male; D009609:Nitrous Oxide / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors; D014805:Vitamin B 12 / Q000031:analogs & derivatives / Q000097:blood / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D009609:Nitrous Oxide; D014805:Vitamin B 12