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COMPARATIVE PHASE I AND II MICROSOMAL METABOLISM OF PHENOL IN THREE FISH SPECIES
Kolanczyk, R C., L. E. Solem, J M. McKim, AND P. K. Schmieder. COMPARATIVE PHASE I AND II MICROSOMAL METABOLISM OF PHENOL IN THREE FISH SPECIES. Presented at Joint Regional SETAC/SOT Annual Meetings, USEPA, Duluth, MN, April 9-10, 2002.
In vitro metabolism of phenol at 11 degrees C has been studied using immature adult rainbow (Oncorhynchus mykiss), brook (Salvelinus fontinalis), and lake trout (Salvelinus namaycush) hepatic microsomal preparations. Incubations were optimized for time, cofactor concentration, pH, and microsomal protein concentration. Formation of phase I ring-hydroxylation and phase II glucuronidation metabolites were quantified by the use of HPLC with dual channel electrochemical and UV detection. Metabolism of phenol over a range of substrate concentrations (1 to 150 mM) was quantified in an attempt to calculate the Michaelis-Menten kinetics constants Km and Vmax for hydroquinone, catechol and phenylglucuronide. There appeared to be a species difference in Km values for HQ and CAT formation, with the following rank order of apparent enzyme affinity for substrate: RBT > BKT and LKT. There was no apparent difference in the Km for phenylglucuronide formation. The apparent Vmax for phenylglucuronide formation was equal in RBT and BKT but greater than that observed in LKT. These experiments provide a means to quantify metabolic activation of xenobiotics in fish to compare activation reactions across aquatic species, nd to provide a basis for the prediction of metabolic pathways and rates in fish. This abstract does not necessarily reflect EPA policy.
Record Details:Record Type: DOCUMENT (PRESENTATION/ABSTRACT)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL HEALTH AND ENVIRONMENTAL EFFECTS RESEARCH LAB
MID-CONTINENT ECOLOGY DIVISION
MOLECULAR & CELLULAR MECHANISMS RESEARCH