Lack of correlation between hepatic microsomal progesterone 21-hydroxylase activity and the excretion of acidic metabolites in rabbit urine.

Hepatic microsomes were prepared from liver sections removed from anesthetised New Zealand White rabbits. Two groups of rabbits, distinguished by different levels of progesterone 21-hydroxylase, were compared for in vitro and in vivo metabolism of [3H]deoxycorticosterone/[14C]progesterone mixtures. In vitro, microsomes with low 21-hydroxylase activity gave significantly lower yields of pregnenoic acid than those with higher 21-hydroxylase activities. In vivo, these differences were not evident from an examination of the 3H/14C ratios of acidic urinary metabolites.