Relaxation of rabbit cavernous smooth muscle to 17beta-estradiol: a non-genomic, NO-independent mechanism.
OBJECTIVE
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 micromol/L) or L-NAME (10 micromol/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.


CONCLUSIONS
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.
Kim
Sae-Chul
SC
Department of Urology, Chung-Ang University Yongsan Hospital, 65-207 Hangang-Ro 3-Ka, Yongsan-Ku, Seoul 140-757, Korea. saeckim@unitel.co.kr
Seo
Kyung-Kun
KK
Myung
Soon-Chul
SC
Lee
Moo Yeol
MY
D000818:Animals; D003609:Dactinomycin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology*; D066298:In Vitro Techniques; D007202:Indicators and Reagents; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D052250:Nitric Oxide Synthase Type III; D009638:Norepinephrine / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D010413:Penis / Q000187:drug effects*; D010455:Peptides / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D011817:Rabbits; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D004791:Enzyme Inhibitors; D007202:Indicators and Reagents; D010455:Peptides; D026902:Potassium Channel Blockers; D014662:Vasoconstrictor Agents; D003609:Dactinomycin; D004958:Estradiol; C064719:iberiotoxin; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D019331:NG-Nitroarginine Methyl Ester; D009638:Norepinephrine