title: Comparison of cytochrome P-450 content and activities in liver microsomes of seven animal species, including man.
abstract: The cytochrome P-450 content found in human livers obtained post mortem was between 0.21-0.42 nmol/mg protein. The kinetic parameters of the mono-oxygenase activities--Km and Vmax--were determined in liver microsomes for N-demethylation (aminopyrine, benzphetamine, ethylmorphine), O-demethylation (4-nitroanisole), O-deethylation (7-ethoxycoumarin) and hydroxylation (benzo[a]pyrene), in an attempt to establish an inter-species comparison between man and the six animal species studied. The four substrates studied (aminopyrine, benzphetamine, ethylmorphine, benzo[a]pyrene) were shown to be less active in humans than the male rat, which is the most commonly used model. However, other animal species, such as the female Sprague-Dawley rat and the pig, are much more similar to man. From a procedural point of view, the optimal substrate concentrations vary from one experimental species to another. Due to the apparent Km observed, for example, the activities of the guinea-pig require a higher substrate concentration.
mesh_terms: D000328:Adult; D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D005260:Female; D006168:Guinea Pigs; D000882:Haplorhini; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008862:Microsomes, Liver / Q000201:enzymology*; D006899:Mixed Function Oxygenases / Q000378:metabolism; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D013045:Species Specificity; D013552:Swine
chemical_list: D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases