Specific binding sites for [3H]Ro 5-4864 in rat prostate and seminal vesicle

1. The peripheral-type benzodiazepine receptor was characterized in rat prostate and seminal vesicle using [3H]Ro 5-4864 as radioligand. 2. The affinity of this radioligand for this receptor was higher in rat prostate (KD = 4.36 +/- 1.02 nM) than in seminal vesicle (KD = 8.45 +/- 1.34 nM). 3. The density of binding sites obtained in these two tissues was Bmax = 4164 +/- 873 fmol/mg in prostate and 5978 +/- 1022 fmol/mg in seminal vesicle. 4. The [3H]Ro 5-4864 binding was inhibited non-competitively by atractyloside and alpha,beta-methylene-ATP, suggesting a modulation by the ADP/ATP mitochondrial carrier. 5. Flutamide was able to displace bound [3H]Ro 5-4864 with an IC50 similar to protoporphyrin IX.