DECREASED CONTRACTILE EFFECT OF ENDOTHELIN-1 ON HYPERPLASTIC PROSTATE

1. The contractile activity, binding activity and localization of endo thelin (ET)-1 were evaluated in human nonhyperplastic (control) and hy perplastic prostates. 2. ET-1 caused contraction of both prostates in a dose-dependent manner. However, this contraction was markedly decrea sed in hyperplastic prostates. 3. B-max and K-d values of hyperplastic prostates were greater than those of the control. 4. The muscle and p roliferative epithelium of hyperplastic prostates showed strong staini ng for the anti-ET-1 antibody. However, the glandular epithelium of co ntrol prostates was weakly stained. 5. These findings indicate that re sponsiveness to ET-1 is decreased, though the ET-1 and ET-1 receptors increase in the hyperplastic prostate. Namely, the increase in ET-1 re ceptors is not effective in regulating the contractile response of the prostate, because its expression is rather dominant in proliferated g land. 6. These suggest-that ET-1 may not have an important role in the release of the obstructive symptoms of benign prostatic hypertrophy.