title: Studies on the metabolism of diethyl 4-nitrophenyl phosphorothionate (parathion) in vitro.
abstract: 1. The metabolism of the phosphorothionate parathion in vitro was examined by using [(32)P]parathion and microsomes isolated from the livers of various animal species. 2. The major metabolic products of parathion in this system in vitro were identified as diethyl 4-nitrophenyl phosphate (paraoxon), diethyl hydrogen phosphate, diethyl hydrogen phosphorothionate and p-nitrophenol. 3. The reaction leading to the formation of diethyl hydrogen phosphorothionate and p-nitrophenol requires the same cofactors (NADPH and oxygen) required for metabolism of parathion to its active anti-acetylcholinesterase paraoxon. 4. The enzyme activity towards parathion per unit weight of liver is increased some 65-130% by pretreatment of male rats with phenobarbital and 3,4-benzopyrene. 5. The metabolism of parathion is inhibited by incubation in a nitrogen atmosphere and in an atmosphere containing carbon monoxide. Pure oxygen is also inhibitory. These results are discussed in terms of a deficiency of oxygen for maximal activity as well as the lability of some component of the system to oxidation.
mesh_terms: D000818:Animals; D001580:Benzopyrenes / Q000494:pharmacology; D002248:Carbon Monoxide / Q000494:pharmacology; D002855:Chromatography, Thin Layer; D004798:Enzymes / Q000378:metabolism; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism*; D008297:Male; D051379:Mice; D008861:Microsomes / Q000378:metabolism*; D009249:NADP / Q000494:pharmacology; D009584:Nitrogen / Q000494:pharmacology; D009596:Nitrophenols / Q000378:metabolism; D010100:Oxygen / Q000494:pharmacology; D010278:Parathion / Q000378:metabolism*; D010634:Phenobarbital / Q000494:pharmacology; D010710:Phosphates / Q000378:metabolism; D010759:Phosphorus Isotopes; D051381:Rats
chemical_list: D001580:Benzopyrenes; D004798:Enzymes; D009596:Nitrophenols; D010710:Phosphates; D010759:Phosphorus Isotopes; D009249:NADP; D010278:Parathion; D002248:Carbon Monoxide; D009584:Nitrogen; D010100:Oxygen; D010634:Phenobarbital