The relationship between hepatic microsomal biphenyl 2-hydroxylase, 4-hydroxylase and urinary glucaric acid excretion in the rat.

Treatment of rats with phenobarbital (PB) caused an increase in microsomal biphenyl 4-hydroxylase activity and urinary glucaric acid excretion. Hepatic microsomal biphenyl 4-hydroxylase activity was correlative with urinary glucaric excretion in PB-treated rats. Hepatic microsomal biphenyl 2-hydroxylase activity was not correlated with urinary glucaric excretion in PB, 3-methylcholanthrene (3-MC)- and beta-naphthoflavone (beta-NF)-treated rats. Pretreatment of rats with carbon tetrachloride caused decreases in urinary glucaric acid excretion and biphenyl 2- and 4-hydroxylase activities. On the other hand, pretreatment with cobalt chloride caused decreases of these enzyme activities, but not of urinary glucaric acid excretion. These findings suggest that the urinary glucaric acid level would not always provide an index for assessment of hepatic drug metabolizing enzyme activity. These findings suggest that the urinary glucaric acid level would not always provide an index for assessment of hepatic drug metabolizing enzyme activity.