Hepatic amidopyrine N-demethylase activity in the calf

Abstract

The daily oral administration to calves of phenobarbitone (20 mg./kg.) produces an increase in the activity of amidopyrine N-demethylase in the liver. The induced activity reaches a peak at about 14 days and then falls slowly in spite of the continued administration of phenobarbitone. A single dose of alpha-cyanato-napthalene (ANIT) reduced enzyme activity within 48 hours as also did a single dose of carbon tetrachloride. The effect of a single dose of halothane on hepatic enzyme activity was much less. Pretreatment with phenobarbitone had no influence on the hepatotoxic effect of ANIT whereas pretreatment considerably increased the toxic effects of carbon tetrachloride and of halothane.