[Effect of age and inductors on UDP-glucuronyltransferase activity]

This experiments were carried out on: 0.5-, 1-, 2-, 4-, 8-, 12-, 20- and 28-months old Wistar males rats. Before they were killed the animals received by intraperitoneal injection: phenobarbital (50 mg/kg in 0.9% saline 72- and 48-hr before the death), beta-naphthoflavone (20 mg/kg in sesame oil for 3 consecutive days prior to sacrifice), dexamethasone (10 mg/kg; see beta-naphthoflavone). All animals were decapitated after 24 hr of starvation. The livers were rinsed with cold 0.9% saline. Hepatic microsomes were prepared as described Dallner. The UDP-glucuronyltransferase activities with p-nitrophenol as aglycone were determined according to Burchell and Weatherill and protein concentration was measured as described Lowry et al. The activity of examined enzyme had maximal value in youngest rats, but in older one it was decreased. Minimum was observed in 8-month old animals and all older. Pretreatment of rats with beta-naphthoflavone significantly increased glucuronidation especially in sexually mature animals. The date obtained with phenobarbital and dexamethasone pretreatment rats suggested lower magnitude of stimulation of UDP-glucuronyltransferase than beta-naphthoflavone and lack of effect respectively.