STRAIN DIFFERENCES IN RAT-LIVER UDP-GLUCURONYLTRANSFERASE ACTIVITY TOWARDS ANDROSTERONE

Male Donryu, Wistar and Wistar King rats showed discontinuous variations in hepatic microsomal UDP-glucuronyltransferase activities towards androsterone, but not towards testosterone, bilirubin, phenolphthalein and 4-nitrophenol. Fresh microsomal fraction with a low transferase activity towards androsterone formed 0.049-0.080 nmol of glucuronide/min per mg of protein, whereas fresh microsomal fraction with a high transferase activity towards androsterone formed 0.335-0.557 nmol of glucuronide/min per mg of protein. The microsomal fraction with low enzyme activity towards androsterone was not stimulated by treatment with Triton X-100 or freezing and thawing. In contrast, male Long Evans and Sprague-Dawley rats did not exhibit such diversity.