Plasma Antipyrine Half-Life and Hepatic Microsomal Antipyrine Hydroxylase Activity in Rabbits

Abstract

Plasma antipyrine half-lives were deter mined on 12 castrated albino rabbits: 6 kept at normal atmospheric conditions and 6 exposed to carbon monoxide (CO). Cytochrome P-450 (P-450) content and anti pyrine hydroxylase activity were determined in the hepatic microsomal fraction of all animals. Although a poor correlation occurred between antipyrine half-life (t½) and P-450 content (–0.46), a correlation coefficient of –0.79 was obtained for plasma antipyrine half-life and antipyrine hydroxylase activity in hepatic microsomes. The mean plasma antipyrine half-life was 1.06 h for the animals. The half-lives of antipyrine did not change significantly after short-term (2 h) or after long-term (130 h) exposure to carbon monoxide gas (0.018 %, v/v). In addition the carbon monoxide exposed group did not show significant differences from the control group regarding P-450 concentrations or antipyrine hydroxylase activity.