Variations in hepatic microsomal drug metabolism in C57Bl/6 mice from three different suppliers

Drug metabolism by hepatic microsomal and soluble fractions was compared in male C57Bl/6 mice purchased from three different suppliers. Mice were studied at 9 weeks of age after having been purchased either as weanlings or at 8 weeks of age. Significant differences were found in the specific activity of several mixed-function oxidase enzymes and in amounts of cytochrome P-450 among the three sources of mice.