Testosterone metabolism in rat liver cytosolic androgen binding assays.

Testosterone metabolism was studied in vitro, using incubation conditions similar to those employed in some adult male rat liver cytosolic androgen receptor assays. Following extraction, thin layer chromatography, and gas chromatography-mass spectrometric analysis, it was observed that testosterone was significantly metabolized in vitro to 5 beta-androstane-3 alpha, 17 beta-diol. These results indicate that gross inaccuracies can be made when estimating the free testosterone concentrations in hepatic cytosolic androgen binding studies.