| Abstract: | Antipyrine plasma half-life (APH) has been used as an indicator of hepatic oxidase activity in rhesus monkeys (Macaca mulatta). Plasma disappearance of 14CH3-N-antipyrine (AP) was measured radiometrically. AP and 3 metabolites were detected using high pressure liquid chromatography. APH was assessed during a 300-day control period and following phenobarbital (PB) pretreatments. Significant interindividual variability was observed requiring that animals be used as their own controls. PB (15 mg/kg i.m., 2/day X 4 days) reduced mean APH values from 81 +/- 12 to 41 +/- 2 min. PB treatment also increased monooxygenase catalyzed aldrin epoxidation, dihydroisodrin hydroxylation and benzo(a)pyrene oxidation measured using liver biopsy homogenates. These parameters permit 'continual' assessment of HMO activity in rhesus monkeys under a variety of experimental conditions. |
