Hydrogen exchange during oxidoreduction and epimerization at C-3 of C19 steroid sulphates in the rat.
Mixtures of 17 beta-hydroxy-5 alpha-[16,16,17 alpha-2H3]androstan-3-one 17-sulphate and 5 alpha-[3 beta (or 3 alpha)-2H]androstane-3 alpha (or 3 beta), 17 beta-diol 17-sulphate were incubated with isolated hepatocytes from female rats or infused intravenously in female rats with bile fistulas. The androstanediols formed were analyzed by gas chromatography-mass spectrometry. Metabolism of 3H-labelled steroids was also studied in corresponding experiments. Isolated hepatocytes rapidly reduced the 3-oxosteroid to the corresponding 3 alpha-hydroxysteroid, which was more rapidly sulphated than the incubated 3 alpha-androstanediol. The 3 alpha-hydroxysteroid was extensively oxidoreduced both in vivo and in isolated hepatocytes. The intermediate formed during oxidoreduction in vivo was incompletely mixed with the infused 3-oxosteroid indicating extrahepatic uptake of the latter. The 3 beta-hydroxysteroid was sulphated without significant oxidoreduction and a minor fraction was converted to 3 alpha-hydroxysteroid both in vivo and in isolated hepatocytes. The incubated 3 beta-hydroxysteroid contributed more to the disulphate of the isolated 3 alpha-hydroxysteroid than to the monosulphate, indicating that the incubated 3-oxosteroid and the intermediate in the inversion were not completely mixed. Deuterium from the 3 beta- or 3 alpha-positions of the incubated [3-2H]androstanediols was not incorporated in androstanediol molecules derived from the 3-oxosteroid. However, both in vivo and in isolated hepatocytes the 5 alpha-[3 alpha-2H]androstane-3 beta,17 beta-diol 17-sulphate molecules which underwent inversion at C-3 retained 50-80% of the deuterium. This indicates that the inversion was not caused by two separate oxidoreductases.
Cronholm
T
T
Department of Physiological Chemistry, Karolinska Institutet, Stockholm, Sweden.
Rudqvist
U
U
D015113:Androstane-3,17-diol / Q000031:analogs & derivatives / Q000378:metabolism*; D000732:Androstanols / Q000378:metabolism*; D000818:Animals; D001646:Bile / Q000378:metabolism; D013196:Dihydrotestosterone / Q000031:analogs & derivatives* / Q000378:metabolism; D005260:Female; D066298:In Vitro Techniques; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D010084:Oxidation-Reduction; D051381:Rats; D011919:Rats, Inbred Strains; D013237:Stereoisomerism; D014316:Tritium
D000732:Androstanols; D013196:Dihydrotestosterone; D014316:Tritium; C056505:17-hydroxyandrostan-3-one 17-sulfate; C056506:androstane-3,17-diol 17-sulfate; D015113:Androstane-3,17-diol