The activities of aminopyrine N-demethylase, aniline 4-hydroxylase and UDP-glucuronyltransferase in tissues of camels, desert sheep and Nubian goats.

1. The activities of the drug-metabolizing enzymes, aminopyrine N-demethylase, aniline 4-hydroxylase and UDP-glucuronyltransferase have been measured in vitro in the liver, kidney and duodenal mucosa of camels, sheep, goats and rats. 2. Enzyme activities were generally higher in the liver, followed by the duodenal mucosa, then the kidney in all species. 3. Male kids had much lower enzyme activity in the liver when compared to adult goats, and in the former animal, no measurable activity could be detected in the duodenal mucosa or kidney. 4. In general, goats seemed to have the highest and camels the lowest enzyme activity when compared to the other species. 5. Some sex differences were noted in the three enzymes studied. In sheep duodenal mucosa and rat liver and duodenal mucosa, males had higher aminopyrine N-demethylase than females. In rat liver and goat duodenal mucosa males had higher aniline 4-hydroxylase than females. Male rats had higher UDP-glucuronyltransferase in liver when compared to females.