ENDOTHELIN RECEPTOR DENSITY IN HUMAN HYPERTROPHIC AND NON-HYPERTROPHIC PROSTATE TISSUE

The amount of endothelin receptors in human prostate tissue was measured by radioligand binding techniques using I-125-Endothelin -1 and -3 (I-125-ET-1, -3). Specimens of the non-hypertrophy group were obtained from 6 patients who underwent total cystectomy under the diagnosis of bladder cancer and those of the hypertrophy group from 6 prostatic hypertrophy patients who underwent open prostatectomy. I-125-ET-1 bound to the prostate tissue with the KD value of 0.033 +/- 0.012 nM in the non-hypertrophy group and with the KD value of 0.035 +/- 0.012 nm in the hypertrophy group. I-125-ET-3 bound to the prostate tissue with the KD value of 0.023 +/- 0.011 nM in the non-hypertrophy group and with the KD value of 0.029 +/- 0.016 nM in the hypertrophy group. The KD values were not significantly different between the hypertrophy and nonhypertrophy groups. The KD values of I-125-ET-1 and I-125-ET-3 were similar. The Bmax values (fmol/mg protein) of I-125-ET-1 binding to the prostate tissue were 32.18 +/- 3.69 to the non-hypertrophy group and 85.66 +/- 20.65 to the hypertrophy group. The Bmax values (fmol/mg protein) of I-125-ET-3 binding to the prostate tissue were 27.48 +/- 5.25 to the non-hypertrophy group and 75.90 +/- 13.46 to the hypertrophy group. The Bmax values of both I-125-ET-1 and I-125-ET-3 were significantly higher in the hypertrophy group than in the non-hypertrophy group. Benign prostatic hypertrophy was found to increase the density of endothelin receptors in human prostate tissue, suggesting that endothelins modulate the pathophysiology of benign prostatic hypertrophy.