Tissue slice technology for assessing alterations in fish hepatic phase I and phase II XME activity

• Published in: Marine environmental research 1998-07, Vol.46 (1), p.61-63
• Main Authors: Kane, A.S., Thohan, S., Weiner, M.
• Format: Article
• Language: English
• Subjects: Agnatha. Pisces; Animal, plant and microbial ecology; Applied ecology; benzo(a)pyrene; Biological and medical sciences; Brackish; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on vertebrates; Freshwater; Fundamental and applied biological sciences. Psychology; Ictalurus punctatus; Marine; Oncorhynchus mykiss; Pisces; umbelliferone; xenobiotic metabolizing enzymes
• ISSN: 0141-1136; 1879-0291
• DOI: 10.1016/S0141-1136(97)00061-5

Alterations to hepatic xenobiotic metabolizing enzymes (XMEs) is an important biomarker of contaminant exposure in aquatic toxicology. Measurement of XMEs in fish liver slices in vitro is an emerging tool for examining enzyme activity and response within the intact 3-D architecture of the liver tissue. We examined integrated phase I/phase II, and phase II metabolism of XMEs from liver slices in control and B[a]P-treated rainbow trout and channel catfish. Fluorescent assay substrates to measure rates of metabolism included 7-methoxycoumarin (7-MC), 7-ethoxycoumarin (7-EC) and 7-hydroxycoumarin (7-HC). Time-dependent increases in metabolism, and a lower rate of 7-MC metabolism compared with 7-EC metabolism, were observed at all time points for both fish species. In rainbow trout, B[a]P pretreatment caused a 10-fold increase in phase I metabolism of both 7-MC and 7-EC, and a 1.6-fold increase in phase II metabolism of 7-HC. Phase I activity in channel catfish was not notably altered by B[a]P pretreatment. However, B[a]P pretreatment in channel catfish caused a 48% decrease in phase II metabolism of 7-HC. These results indicate differences in baseline and B[a]P-altered XME profiles between rainbow trout and channel catfish.