Xenobiotic biotransformation in wild birds: activity, induction, characterization and comparison with rat and mouse microsomal enzymes

Abstract

1. Benzo[a]pyrene hydroxylase, aminopyrine demethylase and glutathione S-trans-ferase activities in hepatic and extrahepatic tissues of five wild birds, rat and mouse were compared. 2. Hepatic benzo[a]pyrene hydroxylase of wild pigeon was at least three times higher than that of rat or mouse. Hepatic aminopyrine demethylase and GSH S-transferase activities of wild birds were lower than those of rodents. 3. Renal GSH S-transferase of wild birds was 2-3 times more than in rat and mouse. 4. Avian benzo[a]pyrene hydroxylase activity of hepatic and renal tissue was linear up to 3.0mg enzyme protein with pH optima of 7.4 and 7.2, at 42°C Apparent K_m values were 11.76 and 3.33 µM respectively. 5. Hepatic enzyme activity was induced four-fold by 3-methylcholanthrene and about two-fold by phenobarbitone administration.