CHARACTERIZATION AND DIFFERENTIATION OF PERIPHERAL-TYPE BENZODIAZEPINE RECEPTORS IN RAT AND HUMAN PROSTATE

We have characterized the presence of peripheral-type benzodiazepine r eceptor in rat and human prostate. [H-3] PK 11195, a putative antagoni st, showed a greater affinity for this receptor in rat prostate (K-D = 1.71 +/- 0.18 nM) than in human (K-D = 15.23 +/- 1.30 nM) In human, t he peripheral-type benzodiazepine receptor density (B,, 13,575 +/- 1,9 29 fmols/mg) is double that in rat (B-max = 6,345 +/- 314 fmols/mg). [ H-3] RO 5-4864, an agonist, showed a low affinity (K-D = 188.38 +/- 16 .46 nM) for human peripheral-type benzodiazepine receptor subtype. we did not detect any difference between the population of this receptor in control human prostate and that in hyperplastic specimens. In rat, bound [3H] PK 11195 was partially inhibited by specific ligands of mit ochondrial ADP/ATP carrier. This characteristic does not occur in huma n prostate. A common trait of both rat and human prostate peripheral-t ype benzodiazepine receptors is the competitive displacement of bound [H-3] PK 11195 by nitrendipine and the blockers of the adenosine uptak e system.