Metabolism of Bis(Tributyltin)Oxide by Estuarine Animals

A variety of estuarine animals, including crabs (Callinectes sapidus), fish (Leistomus canthurus) and shrimp (Penaeus aztecus), were able to metabolize TBTO which entered the animal via food or water. Hepatic tissues, fish intestine or crab stomach appeared to be important organs for metabolism of TBTO, while the gill, although an important organ for uptake via the water, did not appear to be important in TBTO metabolism. In vivo studies showed dibutyltin to be the major metabolite for these studies. The major TBTO metabolites when using microsomal preparations from fish liver or crab hepatopacreas were beta-hydroxybutyldibutltin and dibutyltin. Oysters (Crassostrea virginica) showed only a limited ability to metabolize TBTO. The cytochrome P-450 dependent mixed-function oxygenase (MFO) system appeared to be the enzyme system responsible for the oxidation of TBTO in microsomes from fish liver and crab stomach. TBTO oxidation by crab stomach or fish liver microsomes required NADPH and oxygen and was inhibited by carbon monoxide.