Catalytic and Immunochemical Characterization of Cytochrome P450 Isozyme Induction in Dog Liver

The purpose of this study was to characterize hepatic cyto-chrome P450 induction in the dog by phenobarbital, /3-naph-thoflavone, dexamethasone, and isoniazid using catalytic activities and Western blots with antibodies prepared against rat cyto-chrome P450 isozymes. Male beagle dogs were treated with pheno-barbital (10 mg/kg for 2 days and 30 mg/kg for the following 5 days), /3-naphthoflavone (50 mg/kg for 5 days), or isoniazid (10 mg/kg for 2 days and 30 mg/kg for the following 5 days). Female beagle dogs were treated with dexamethasone (50 mg/kg for 5 days). Increases in the liver/body weight ratio were observed after treatment of dogs with phenobarbital (133 % of control) and dexa-methasone (153%). Total cytochrome P450 content was increased as a percentage of control after treatment with phenobarbital (264%) and /5-naphthoflavone (186%), while it slightly decreased after treatment with isoniazid (54%) and dexamethasone (71%)