Aflatoxin B 1 acute effects on three hepatic urea cycle enzymes using semiautomated methods: A model for Reye's syndrome

Abstract

Urea cycle enzyme activities may be determined through the colorimetric analysis of urea and citrulline, which are intermediates in the cycle. A new semiautomated method was used to measure the activities of carbamyl phosphate synthetase, ornithine transcarbamylase, and arginase in liver samples from male Fischer rats (120–150 g) given a toxic dose of aflatoxin B 1. Carbamyl phosphate synthetase and ornithine transcarbamylase activities were 61 and 67%, respectively, of control values, 24 hr after a 3 mg/kg dose. Arginase activity was within the normal range. This pattern of ureas cycle enzyme activities is similar to that reported in biopsy specimens from children with Reye's syndrome.