Extrahepatic xenobiotic metabolism in North-European freshwater fish

1. 1. Cytochrome P450 and monooxygenase activity and glucuronidation were measured in the gills, intestine, heart and kidney as well as in the liver of vendace, perch and roach and rainbow trout for comparison. 2. 2. Cytochrome P450 content and the specific monooxygenase activities were always highest in the liver. In the rainbow trout and vendace the renal 7-ethoxycoumarin- O-deethylase and in the roach the renal 3,4-benzpyrene hydroxylase activity was about half of that in liver. The activities in gills were relatively high in roach and vendace. In rainbow trout, perch and roach the intestinal activities were easily detectable. 3. 3. In all fish high UDPglucuronosyltransferase activities were found in the liver and intestine. In vendace and roach both the gills and the kidney showed, however, even higher specific activities. 4. 4. The rainbow trout showed higher hepatic and intestinal biotransformation activities than the other species.