title: Inhibition of fetal methionine synthase by nitrous oxide.
abstract: The activity of the enzyme methionine synthase in fetal and maternal liver was investigated before and after exposure to nitrous oxide. Timed-pregnant rats on day 19 of gestation were exposed to either 10% or 50% nitrous oxide for various times up to 240 min. After exposure, fetal and maternal livers were removed and methionine synthase activity assayed. Normal methionine synthase activity in the fetus was about 50% of that in the mother. Both fetal and maternal methionine synthase activity decreased progressively with increasing time of exposure to nitrous oxide and recovered only slowly after the agent was discontinued.
mesh_terms: D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase / Q000037:antagonists & inhibitors*; D000818:Animals; D005260:Female; D005333:Fetus / Q000187:drug effects / Q000201:enzymology*; D008099:Liver / Q000201:enzymology; D008431:Maternal-Fetal Exchange; D008780:Methyltransferases / Q000037:antagonists & inhibitors*; D009609:Nitrous Oxide / Q000494:pharmacology*; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
chemical_list: D008780:Methyltransferases; D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase; D009609:Nitrous Oxide