HEPATIC MICROSOMAL MIXED-FUNCTION OXIDASE ACTIVITIES IN SEVERAL MARINE SPECIES COMMON TO COASTAL FLORIDA

1. NADPH-dependent hepatic microsomal mixed-function oxidase activities were measured in a number of marine vertebrate and invertebrate species common to the Florida Atlantic coast, using benzo(a)pyrene, 7-ethoxycoumarin, benzphetamine and aniline as substrates. Optimal assay conditions were established using sheepshead hepatic microsomes. 2. Mixed-function oxidase activity was easily detected in hepatic microsomes from teleost and elasmobranch fish, but was low or undetectable in hepatopancreas microsomes from crustaceans. However, the cytochrome P-450 content of hepatopancreas microsomes often exceeded that found in microsomes from teleost or elasmobranch liver. 3. Mixed-function oxidase activity in microsomes prepared from extrahepatic organs was usually much lower than was found in hepatic microsomes. However, for two teleost species (sheepshead and black drum), benzphetamine N-demethylase activity of gill microsomes approached that found in hepatic microsomes. 4. The temperature optimum for in vitro mixed-function oxidase activity was higher in the Florida fish tested than has been reported for cold-water acclimated marine or freshwater fish. © 1979.