A comparison of in vitro and in vivo methods for evaluating alterations in hepatic drug metabolism following mercuric chloride administration

Abstract

Mercuric chloride was administered once i.p. to female Fischer-344 rats at doses of 0, 0.2, 0.6 and 1.8 mg/kg. Although there were no alterations in the urinary excretion of lactate dehydrogenase, significant elevations in the activities of urinary (U) alkaline phosphatase, glutamic-pyruvic transaminase (GPT) and glutamic-oxalacetic transaminase (GOT) indicated that mercuric chloride was nephrotoxic. There was no evidence of hepatotoxicity as hepatic glucose-6-phosphatase and serum sorbitol dehydrogenase were essentially unaffected by mercuric chloride administration. The activities of ethylmorphine demethylase, hexobarbital oxidase and aldrin epoxidase determined in vitro were not inhibited by mercuric chloride although aniline hydroxylase activity was decreased. Of the four phase-II reactions measured, only the glucuronidation of chloramphenicol was diminished by treatment with mercuric chloride. Results from the in vivo studies on the metabolism of lindane, which indicated no change in the excretion of free or conjugated metabolites, were in close agreement with the in vitro data suggesting that the nephrotoxic effects of mercuric chloride do not alter the urinary excretion of the model substrate lindane.