Area density of smooth muscle cells and response to endothelin 1 in human hyperplastic prostate

Background: a-Agonists and endothelins (ETs) are the only agents that have been proved to induce significant contraction of the prostate. Although the response to phenylephrine (PE) is dependent on the quality of smooth muscl e (SM) within the prostate, it is not clear whether the response to ET-1 is also influenced by SM density. We evaluate the relationship between contra ctile responsiveness to ET-1 and the area density of SM of the human prosta te. Materials and Methods: Specimens were obtained from 17 patients with prosta tic hyperplasia that underwent transurethral resection of the prostate. Spe cimens were used for isometric tension study (PE, KCI and ET) and also for quantitative morphometric analysis. Results: PE and ET-1 induced dose-dependent contractile responses. There we re no significant differences in the average maximum response (E-max) to th ese two agents. E-max to KCl and PE showed direct positive correlations wit h the area density of SM. E-max to ET-1 also showed a positive correlation with the SM density, although this relationship was weaker than those for t he other two agents. Moreover, there was a strong positive relationship bet ween E-max to PE, KCl and that to ET-1. Conclusions: The area density of SM appeared to significantly influence the contractile response to ET-1 as well as the response to PE and KCl. Copyri ght (C) 2000 S. Karger AG. Basel.