EFFECTS OF ENDOTHELIN-1 ON THE SMOOTH MUSCLE CONTRACTILITY OF HUMAN URINARY BLADDER, SPERMATIC CORD AND PROSTATIC ADENOMA

Effects of endothelin-1 (ET-1) on the smooth muscle contractility of human detrusor, spermatic cord and hypertrophied prostatic adenoma were examined in muscle bath studies. ET-1 increased the contractile forces of all above smooth muscle strips in concentration dependent manner. The contractile force induced by 10-6M ET-1 was approximately 30% of that induced by 3×10-5M carbachol in detrusor muscle strips, approximately 40% of that induced by 10-4M norepinephrine in spermatic cord muscle strips and almost equal to that induced by 10-5M phenylephrine in prostatic adenoma muscle strips. The contractions induced by ET-1 in those muscle strips were not inhibited by any of tetrodoxine, atropine, phentolamine, propranolol and indomethacine. These results suggest that ET-1 may act as a constrictor on lower urinary tract and genital smooth muscles and especially on prostatic adenoma and that ET-1 may affect those smooth muscles directly not through autonomic receptors or prostaglandins.