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Characterization and differentiation of peripheral-type benzodiazepine receptors in rat and human prostate

Abstract:

We have characterized the presence of peripheral-type benzodiazepine receptor in rat and human prostate. [3H] PK 11195, a putative antagonist, showed a greater affinity for this receptor in rat prostate (KD = 1.71 ± 0.18 nM) than in human (KD = 15.23 ± 1.30 nM). In human, the peripheral-type benzodiazepine receptor density (Bmax = 13,575 ± 1,929 fmols/mg) is double that in rat (Bmax = 6,345 ± 314 fmols/mg). [3H] Ro 5-4864, an agonist, showed a low affinity (Kp = 188.38 ± 16.46 nM) for human peripheral-type benzodiazepine recetor subtype. We did not detect any differnces 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 mitochondrial ADP/ATP carrier. This characteristic does not occur in human prostate. A common trait of both rat and human prostate peripheral-type benzodiazepine receptors is the competitive displacement of bound [3H] PK 11195 by nitrendipine and the blockers of the adenosine uptake system. © 1994.