Comparison of hepatic drug metabolizing enzymes in three-month-old lambs and kids

1. The comparative activity of hepatic cytochrome P-450 monooxygenase system, glucuronyltransferase, glutathione S-transferase and N-acetyltransferase was studied in three-month-old male and female Lacaune lambs and male Saanen kids. 2. The study of mixed-function oxidase components showed that total cytoehromc P-450 ranged from 0.54 in kids to 0.85–0.88 nmol/mg−1 in lambs. Male lambs had higher levels than kids (122–165%) for aminopyrine, benzphetamine, ethylmorphine and erythromycin demethylases or benzo(a)pyrene hydroxylase whereas NADPH-cytochrome c reductase was 1.19-fold lower in lambs. 3. Sex-related changes were observed in lambs in case of microsomal benzo(a)pyrene hydroxylase activity which appeared 1.31-fold more potent in male liver. Cytosolic N-acetyltransferase accepting sulfamethazine as substrate was about 8-fold higher in female than in male lambs. 4. The analysis of samples from various liver lobes, indicated the heterogenous distribution of micro- somal proteins which is related to higher concentrations of both cytochrome b5, NADPH-cytochrome c reductase and p-nitrophenol glucuronyltransferase in left lobes.