title: Further studies on microsomal drug metabolizing enzyme activity and protein levels in animal models showing different susceptibilities to aflatoxicosis.
abstract: 1. The total protein content and the activities of aniline hydroxylase and p-aminopyrine N-demethylase were measured in the microsomal fraction of rat, mouse, duck, pigeon and turkey. The relative Km values of the enzymes were also determined. 2. The microsomal protein content and the enzyme activities in the birds were lower than that in the rodents. Km values for aniline hydroxylase and p-aminopyrine N-demethylase were higher in birds than in either rat or mouse. 3. The microsomal protein content of mouse was relatively lower than that in rat, although its aniline hydroxylase and p-aminopyrine N-demethylase activities were higher than those in the rat. Km values for aniline hydroxylase in mouse and rat were 0.98 and 1.25 mM, respectively, while the Km values for p-aminopyrine N-demethylase in mouse and rat were 0.55 and 0.62 mM, respectively. 4. These results are discussed in relation to the species differences in susceptibility of animals to toxic or carcinogenic substances.
mesh_terms: D000348:Aflatoxins / Q000633:toxicity*; D000818:Animals; D010856:Columbidae / Q000378:metabolism; D004372:Ducks / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D051379:Mice / Q000378:metabolism; D008862:Microsomes, Liver / Q000201:enzymology*; D008954:Models, Biological; D004364:Pharmaceutical Preparations / Q000378:metabolism*; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains / Q000378:metabolism; D013045:Species Specificity; D014422:Turkeys / Q000378:metabolism
chemical_list: D000348:Aflatoxins; D004364:Pharmaceutical Preparations; D011506:Proteins