Dihydrotestosterone and 3 alpha-androstanediol dynamics in the normal, involuted, and hyperplastic canine prostate.

Perfusion of canine prostatic tissue with [1, 2-3H] 5 alpha-androstane-3 alpha, 17 beta-diol and [4-14C] dihydrotestosterone and the measurement of the isotopic concentrations at the steady state were used to calculate the metabolic dynamics of these steroids by prostatic tissue obtained from normal, castrated or androgen-treated dogs. From the results it was concluded that: Entry of both steroids into the tissue was similar, and no saturation was observed with increasing concentrations of these androgens in the perfusion medium. In contrast, the entry of both steroids was reduced when the perfusion buffer was replaced with diluted plasma. Dihydrotestosterone in prostatic tissue was present in a diffusible form, whereas 3 alpha,17 beta-androstanediol was not. The conversion of 3 alpha, 17 beta-androstanediol to dihydrotestosterone was always higher than the conversion of dihydrotestosterone to 3 alpha, 17 beta-androstanediol; thus, the oxidative pathway was favored. The entry and uptake of both androgens was greatly reduced in those prostates excised from castrated dogs. The uptake of dihydrotestosterone by normal prostatic tissue was 3- to 6-fold higher than the uptake of 3 alpha, 17 beta-androstanediol. However, higher intratissular concentrations of dihydrotestosterone were obtained by increasing the concentration of 3 alpha, 17 beta-androstanediol perfused over that observed by increasing the concentration of dihydrotestosterone perfused. In the hyperplastic tissue, the entry, uptake and metabolism of the two androgens were similar to those observed in the normal gland, but their intratissular concentrations were found to be higher.