Abstract
To evaluate an effect of pathological liver damage on the conjugation of cyclohexane metabolites, rats were pretreated with 50% $CCl_4$ dissolved in olive oil (0.1 ml/100 g body weight) 10 or 17 times intraperitoneally at intervals of every other day. On the basis of liver function, the animals pretreated with $CCl_4$ 10 times were identified as acutely liver damaged ones and the animals pretreated with $CCl_4$ 17 times were identified as severly liver damaged ones. To these liver damaged animals, cyclohexane (a single dose of 1.56 g/kg body weight, i.p.) was administered at 48 hr after the last injection of $CCl_4$. The rats were sacrificed at 4 or 8 hr after injection of cyclohexane. The cyclohexane metabolites, cyclohexanol (CH-ol), cyclohexane-1,2-diol (CH-1,2-diol), cyclohexane-1,4-diol (CH-1,4-diol), and their glucuronyl conjugates and cyclohexanone were detected in the urine of cyclohexane treated rats. The urinary concentration of cyclohexane metabolites was generally more increased in liver damaged animals than normal ones, and the increasing rate was higher in $CCl_4$ 17 times injected rats than 10 times injected ones. And liver damaged.ats, especially $CCl_4$ 17 times treated ones, had an enhanced ability of glucuronyl conjugation to CH-ol analogues compared with normal group. Futhermore, CH-1,2 and 1,4-diol were all conjugated with glucuronic acid in $CCl_4$ 17 times injected animals. On the other hand, the increasing rate of activities of hepatic cytochrome P450 dependent aniline hydroxylase, alcohol dehydrogenase and urine diphosphate glucuronyl transferase was higher in 17 times $CCl_4$-treated rats compared with normal and $CCl_4$ 10 times injected animals. Taken all together, it is assumed that an increased urinary excretion amount of cyclohexane metabolites in liver damaged rats might be caused by an increase in the activities of cyclohexane metabolizing enzymes. And enhanced conjugating ability of CH-ol in liver damaged animals and novel finding of conjugating form of CH-1,2 and 1,4-diol might be caused by increase in the activity of hepatic diphosphouridine glucuronyltransferase.