Temperature Acclimation of Xenobiotic Metabolizing Enzymes in Cultured Hepatocytes and Whole Liver of the Gulf Toadfish, Opsanus beta

Abstract

Changes in cytochrome P-450 and microsomal and soluble protein content and the activities of several microsomal and cytosolic xenobiotic metabolizing enzymes were examined in the whole livers of gulf toadfish, Opsanus beta, following acclimation to 18 or 28 °C and in isolated hepatocytes (prepared from 18 or 28 °C acclimated gulf toadfish) which were maintained in primary culture for 29 d on L-15 media. Cells isolated from both acclimation groups were cultured at 18 and 28 °C. In whole livers, significant differences were found in the activities of sulfotransferase (which showed perfect compensation) and UDP-glucuronosyltransferase (which showed "inverse compensation") between fish acclimated to 18 and 28 °C, but several other trends were obscured by interindividual variation. However, in hepatocyte cultures, temperature adaptations were seen in cytochrome P-450 content and in the activities of the microsomal enzymes aryl hydrocarbon hydroxylase, epoxide hydrolase, and UDP-glucuronosyltransferase. Glutathione-S-transferase activity appeared to be rather temperature insensitive in both whole livers and in cultured hepatocytes. Incomplete temperature acclimation for all enzymes was observed in cultured cells and this may be due to systemic factors which were not present in cell culture media.