Relaxation of rabbit cavernous smooth muscle to 17 beta estradiol: a non-genomic, NO-independent mechanism

Abstract

Aim: To investigate whether estrogen was involved in relaxation of rabbit cavernous smooth muscle. Methods: Relaxation response of the rabbit cavernous smooth muscles to 17beta-estradiol (0.3, 3, 30 and 300 nmol/L) were observed in vitro. The response of the muscle strips to estrogen after incubation with either actinomycin D (10 mumol/L) or L-NAME (10 mumol/L) were also evaluated. Inside-out mode of patch clamp in a single smooth muscle cell was applied to investigate the Maxi-K channel activities. Results: Estrogen caused a dose-dependent relaxation of the strips precontracted with norepinephrine. The maximal response was noted about 10 minutes after treatment. The estrogen-induced relaxation was prevented by neither actinomycin D nor L-NAME, suggesting that the response was not mediated by gene transcription or nitric oxide (NO). Application of 17beta-estradiol increased the Maxi-K channel activities. Conclusion: 17beta-estradiol may be involved in relaxation of rabbit cavernous smooth muscles via a non-genomic and NO independent mechanism. 17beta-estradiol stimulates Maxi-K channel of the rabbit cavernous myocyte.