1.5 mg/rat two times daily

Human benign prostatic hypertrophy tissue that had been obtained by surgery and quickly frozen and stored at -70 "C served as the source of the enzyme. Typically, a 1.8-g portion was thawed, minced, and homogenized in 0.25 M sucrose buffer. The homogenate was centrifuged at 1200 rpm for 10 min, and the supernate was discarded. After the pellet was washed three times in buffer, it was suspended in buffer so that 1.0 mL contained about 300 mg of homogenized tissue. This suspension (0.1 mL) was incubated with 0.01 mL of inhibitor (2g, 17β-Carboxyandrost-4-en-3-one) and 0.1 mL of a mixture containing [3H]testosterone, unlabeled testosterone and dihydrotestosterone, glucose 6-phosphate, glucose-6-phosphate dehydrogenase, and NADP for 30 min at 37 "C. After the incubation, the steroids were extracted with 3.0 mL of ethyl acetate, and the organic phase was separated and evaporated under N2 This extract was spotted onto TLC plates. After the TLC plates were developed in ethyl acetate-cyclohexane (l:l), the [3H]DHT zone was scraped from the plate and counted.