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EFFECTS OF ANESTHESIA (TRICAINE METHANESULFONATE, MS-222) BIOTRANSFORMATION IN RAINBOW TROUT (ONCORHYNCHUS MYKISS)
Citation:
Kolanczyk, R C., P N. Fitzsimmons, J M. McKim, R J. Erickson, AND P. K. Schmieder. EFFECTS OF ANESTHESIA (TRICAINE METHANESULFONATE, MS-222) BIOTRANSFORMATION IN RAINBOW TROUT (ONCORHYNCHUS MYKISS). AQUATIC TOXICOLOGY. Elsevier Science BV, Amsterdam, Netherlands, 64:177-184, (2003).
Description:
Tricaine methanesulfonate (3-aminobenzoic acid eithyl ester methanesulfonate, tricaine, MS-222, Finquel), an anesthetic for fish, has been used extensively in aquatic toxicology to allow surgical procedures for in vivo studies and to permit in vitro preparations of isolated perfused organ, tisue slices, and hepatocytes in several species of fish. Previous work has indicated some confusion over the impact of tricaine on the performance of both Phase I and Phase II enzymes. Efforts to evaluate the effect of tricaine on metabolism were conducted with a microsomal model, an in vitro preparation that can be employed with or without the use of an anaesthetic. Microsomes were prepared from the isolated livers of: (1) control adult rainbow trout, (2) adult rainbow trout exposed to neutralized tricaine (100 mg/L) for a 2-hr period of continuous anesthesia, and (3) adult rainbow trout exposed to neutralized tricaine (100 mg/L) for a 2-hr period followed by a 24-hr period of depuration. No significant differences in P-450 protein or ethoxyresorufin-O-deethylase (EROD) activity were observed in these microsomal assays between tricaine treated trout and controls. Microsomal incubations were also performed with phenol as substrate to assess the effects of tricaine on Phase I and II liver biotransformation by monitoring production of hydroquinone (HQ), catechol (CAT), and phenylglucuronide (PG). The use of tricaine for surgical anesthesia with or without 24-hr recovery did not significantly affect rates of metabolism. In a second experiment, microsomes were prepared from pooled juvenile rainbow trout controls or those exposed to 300 mg/L tricaine for 5-min. No statistical differences from controls were observed in P450 protein levels, EROD activity, phenol ring-hydroxylation, or phenol glucuronidation. The use of tricaine for surgical or in vitro preparations, under these conditions, was not shown to significantly affect measured Phase I and Phase II biotransformation reactions in juvenile or adult rainbow trout.