IDENTIFICATION OF ENDOTHELIN RECEPTORS IN NORMAL AND HYPERPLASIC HUMAN PROSTATE TISSUES

Specific endothelin-l (ET1) binding sites have been demonstrated in me mbranes derived from normal (NP) and benign hyperplasic (BPH) human pr ostate using an I-125-ET1 binding assay. I-125 saturation experiments and Scatchard analysis demonstrated the existence of a homogeneous pop ulation of binding sites with high affinity (Kd(app)) and density (B-m ax), respectively, 106 +/- 15 pM and 1086 +/- 399 fmol/mg protein for NP (n = 5) and 168 +/- 26 pM and 964 +/- 445 fmol/mg protein for BPH ( n = 5). We demonstrated the presence of two subtypes of ET1 receptors, ETA and ETB, by means of the following ET1 competitors: ET2, ET3, and BQ123 (which is selective for the ETA receptor), and IRL1620 and sara fotoxine c (S6c) (which are selective for the ETB receptor). The displ acement curves allowed us to conclude that the large majority (85%) of the ET1 receptors in normal and hyperplasic human prostate are of the A subtype. (C) 1996 Wiley-Liss, Inc.