Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/195506
Type: Artigo de periódico
Title: Relaxation Of Rabbit Corpus Cavernosum By Selective Activators Of Voltage-gated Sodium Channels: Role Of Nitric Oxide-cyclic Guanosine Monophosphate Pathway.
Author: Fernandes de Oliveira, Juliano
Teixeira, Cleber E
Arantes, Eliane C
de Nucci, Gilberto
Antunes, Edson
Abstract: To investigate the capacity of voltage-gated Na(+) channel activators such as batrachotoxin, aconitine, veratridine, Ts1 (formerly Tityus gamma-toxin), and brevetoxin-3 to induce relaxation of rabbit isolated corpus cavernosum (RbCC) and the pharmacologic mechanisms underlying this phenomenon. The voltage-gated Na(+) channels of the corpus cavernosum are essential for erectile function. A number of biologic toxins exert their effects by modifying the properties of these channels. Male New Zealand white rabbits were anesthetized with pentobarbital sodium. Strips of RbCC were transferred to 10-mL organ baths containing oxygenated and warmed Krebs solution. The RbCC strips were connected to force-displacement transducers, and changes in isometric force were recorded using a PowerLab 400 data acquisition system. Corporeal smooth muscle was precontracted submaximally with phenylephrine (10 micromol/L). The binding site-2 (batrachotoxin, aconitine, and veratridine) and binding site-5 (brevetoxin-3) voltage-gated Na(+) channel activators caused slow-onset RbCC relaxations, and the binding site-4 activator Ts1 produced transitory relaxations followed by a return to baseline. The Na(+)channel blockers tetrodotoxin and saxitoxin (0.1 micromol/L each) abolished the relaxations induced by these agonists. Similarly, the nitric oxide synthase inhibitor N(omega)-nitro-l-arginine methyl ester (100 micromol/L) markedly reduced the relaxations and l-arginine (1 mmol/L) restored the relaxations. The soluble guanylyl cyclase inhibitor 1H-[1,2,4] oxidiazolo[4,3-alpha] quinoxalin-1-one (10 micromol/L) reduced the relaxations, and the phosphodiesterase type 5 inhibitor sildenafil (100 nmol/L) significantly potentiated the relaxations by all activators. Our results indicate that the relaxations evoked by selective activators of voltage-gated Na(+) channels are mediated by the release of nitric oxide from nitrergic nerves and the activation of the nitric oxide-cyclic guanosine monophosphate pathway in the smooth muscle cells of erectile tissue.
Subject: Aconitine
Animals
Arginine
Batrachotoxins
Binding Sites
Cyclic Gmp
Guanylate Cyclase
In Vitro Techniques
Insect Proteins
Isometric Contraction
Male
Marine Toxins
Muscle, Smooth
Ng-nitroarginine Methyl Ester
Neurotoxins
Nitric Oxide
Nitric Oxide Synthase
Oxocins
Penile Erection
Penis
Piperazines
Purines
Rabbits
Scorpion Venoms
Sodium Channel Agonists
Sodium Channel Blockers
Sodium Channels
Sulfones
Veratridine
Rights: fechado
Identifier DOI: 
Address: http://www.ncbi.nlm.nih.gov/pubmed/12946781
Date Issue: 2003
Appears in Collections:Artigos e Materiais de Revistas Científicas - Unicamp

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