Transfer of Steroids Across the Hamster Blood Testis and Blood Epididymal Barriers

Hamsters were administered i.v. infusions of solutions containing either l3HI testosterone (T), [3 H) dihydrotestosterone (DHT), or [3 H) progesterone (P). Micropuncture of seminiferous and epididymal tubules and scintillation spectrophotometry of samples was used to determine the concentration of isotope in blood and intraluminal fluid from both types of reproductive tubules. After equilibration, mean isotope concentrations appearing in seminiferous tubule fluid (SNF) were 31%, 24%, and 14% of blood isotope concentrations for 1� HI P, (3 HI T, and l31-IIDHT, respectively. The same figures for cauda epididymidal fluid (CDF) were 33%, 31%, and 20% for (3 HI P, (3 HIT, and (3 HI DHT, respectively. Isotope from [3 Hi T and (3 HI DHT appeared in CDF in significantly greater (P<0.01) concentrations than in SNF. High pressure liquid chromatography (HPLC) of SNF and CDF after systemic infusion of (3 HIP, [3 HIT, and [3 HI DHT was also performed. Isotope collected in SNF during �3 H) T infusion chromatographed primarily with T; in the CDF the isotope (73% of total extractable radioactivity) was associated neither with T nor DHT but with an unidentified highly polar compound(s). Similar conversion occurred in CDF when �3 HI DHT was the infused steroid. 5o Androstane-3a, 17j3 diol was the apparent major metabolite of DHT in SNF. Isotope from [3 HI P appeared mostly as unidentified highly polar compound in