Androgen metabolism in rat skeletal muscle in vitro

Androgen metabolism by the cytosol fraction of rat skeletal muscle was investigated. Testosterone metabolism was low, the main metabolite being 4-androstene-3 alpha,17 beta-diol. In addition, small amounts of 5 alpha-androstane-3 alpha, 17 beta-diol were formed, but no 17 beta-hydroxy-5 alpha-androstane-3-one could be detected. 4-Androstene-3 alpha,17 beta-diol was metabolized only to testosterone in this system of incubation. When 17 beta-hydroxy-5 alpha-androstane-3-one was incubated with muscle cytosol, considerable metabolism to 5 alpha-androstane-3 alpha,17 beta-diol and to 5 alpha-androstane-3 beta,17 beta-diol could be detected. Low 5 alpha-reduction of testosterone and rapid conversion of formed 17 beta-hydroxy-5 alpha-androstane-3-one to 5 alpha-androstane-3 alpha,17 beta-diol and 5 alpha-androstane-3 beta,17 beta-diol gave limited ability of the muscle preparation employed to accumulate 17 beta-hydroxy-5 alpha-androstane-3-one.