[Effect of benign prostatic hypertrophy on the endothelin-1 receptor density in human urinary bladder and prostate]

We measured the amount of binding sites for endothelin-1 (ET-1) in the bladder and prostate in patients with and without benign prostatic hypertrophy (PH and NPH group) using 125I-ET-1. Also the localization of ET-1 binding sites in hypertrophied adenoma was studied using autoradiography. Saturation experiments with 125I-ET-1 revealed that there were single class of saturable high affinity binding sites for 125I-ET-1 in the homogenate of the bladder (dome and base) and prostate (adenoma and capsule). The KD values to the bladder and prostate were not different between PH and NPH group. The Bmax values in the bladder (base and dome) were significantly lower in the PH group. While those in the prostate (adenoma and capsule) were significantly higher in the PH group. Autoradiograms of hypertrophied adenoma showed that ET-1 binding sites were localized to the stromal smooth muscles as well as to the glandular epithelium. These data suggest that ETs affect the pathophysiology of BPH through the changes in receptor density in both the bladder and prostate.