Characterization of testosterone oxidation by rat lung microsomes

To examine the role of multiple forms of cytochrome P-450 in the metabolism of endogenous substrates by lung, the oxidation of testosterone by rat lung microsomes in vitro was characterized and compared to liver. In lung, the majority of metabolism took place at the 16-position, with minor metabolism at the 15 alpha- and 2 beta-positions. Metabolism by lung was up to 200-fold less than liver and, unlike liver, was not sexually differentiated. Although under different regulatory control, similar forms of cytochrome P-450 may contribute to the hydroxylation of testosterone by rat lung and liver.