Slices of ventral prostate and skeletal muscle from castrated rats were incubated with [3H] testosterone. After incubation for two hours, the radioactivity in the prostate was about four times higher than in the muscle.
When the muscle specimens were washed in a hormone-free medium following incubation with [3H] testosterone, most of the radioactivity was lost. In the prostate, on the other hand, this washing procedure removed only a minor part of the radioactivity. After washing at 25°C for 60 min, the concentration of radioactivity in the prostate was about 20 times higher than in muscle. The addition of non-labelled testosterone to the incubation medium reduced the prostatic retention of androgen almost to that in the muscle specimens. Incubation with [3H] 5α-dihydrotestosterone gave essentially the same results as incubation with [3H] testosterone. Furthermore, the retention of androgen by the prostatic tissue was dependent on the conditions of incubation. By increasing the amount of tissue per ml incubation fluid, the retention of androgen by the prostate tissue was markedly reduced. Similarly, by incubation at 0°C, the retention of androgen was diminished both by the prostatic and the muscle specimens.