Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/199364
Type: Artigo de periódico
Title: Role Of A Novel Tetrodotoxin-resistant Sodium Channel In The Nitrergic Relaxation Of Corpus Cavernosum From The South American Rattlesnake Crotalus Durissus Terrificus.
Author: Capel, Rodrigo O
Mónica, Fabíola Z
Porto, Marcovan
Barillas, Samuel
Muscará, Marcelo Nicolás
Teixeira, Simone Aparecida
Arruda, André Moreira Martins
Pissinatti, Lorenzo
Pissinatti, Alcides
Schenka, André A
Antunes, Edson
Nahoum, César
Cogo, José Carlos
de Oliveira, Marco Antonio
De Nucci, Gilberto
Abstract: Coitus in snakes may last up to 28 hours; however, the mechanisms involved are unknown. To evaluate the relevance of the nitric oxide (NO)-cyclic guanosine monophosphate (cGMP)-phosphodiesterase type 5 (PDE5) system in snake corpus cavernosum reactivity. Hemipenes were removed from anesthetized South American rattlesnakes (Crotalus durissus terrificus) and studied by light and scanning electronic microscopy. Isolated Crotalus corpora cavernosa (CCC) were dissected from the non-spiny region of the hemipenises, and tissue reactivity was assessed in organ baths. Cumulative concentration-response curves were constructed for acetylcholine (ACh), sodium nitroprusside (SNP), 5-cyclopropyl-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridine-3-yl]pyrimidin-4-ylamine (BAY 41-2272), and tadalafil in CCC precontracted with phenylephrine. Relaxation induced by electrical field stimulation (EFS) was also done in the absence and presence of N(ω) nitro-L-arginine methyl ester (L-NAME; 100 µM), 1H-[1, 2, 4] oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 10 µM) and tetrodotoxin (TTX; 1 µM). The hemipenes consisted of two functionally concentric corpora cavernosa, one of them containing radiating bundles of smooth muscle fibers (confirmed by α-actin immunostaining). Endothelial and neural nitric oxide synthases were present in the endothelium and neural structures, respectively; whereas soluble guanylate cyclase and PDE5 were expressed in trabecular smooth muscle. ACh and SNP relaxed isolated CCC, with the relaxations being markedly reduced by L-NAME and ODQ, respectively. BAY 41-2272 and tadalafil caused sustained relaxations with potency (pEC(50) ) values of 5.84 ± 0.17 and 5.10 ± 0.08 (N=3-4), respectively. In precontracted CCC, EFS caused frequency-dependent relaxations that lasted three times longer than those in mammalian CC. Although these relaxations were almost abolished by either L-NAME or ODQ, they were unaffected by TTX. In contrast, EFS-induced relaxations in marmoset CC were abolished by TTX. Rattlesnake CC relaxation is mediated by the NO-cGMP-PDE5 pathway in a manner similar to mammals. The novel TTX-resistant Na channel identified here may be responsible for the slow response of smooth muscle following nerve stimulation and could explain the extraordinary duration of snake coitus.
Subject: Acetylcholine
Animals
Callithrix
Carbolines
Crotalus
Cyclic Gmp
Cyclic Nucleotide Phosphodiesterases, Type 5
Dose-response Relationship, Drug
Endothelium, Vascular
In Vitro Techniques
Male
Microscopy, Electron, Scanning
Ng-nitroarginine Methyl Ester
Nitrergic Neurons
Nitric Oxide Synthase
Nitroprusside
Oxadiazoles
Penis
Pyrazoles
Pyridines
Quinoxalines
Sodium Channel Blockers
Sodium Channels
Tetrodotoxin
Vasodilator Agents
Rights: fechado
Identifier DOI: 10.1111/j.1743-6109.2011.02246.x
Address: http://www.ncbi.nlm.nih.gov/pubmed/21477017
Date Issue: 2011
Appears in Collections:Unicamp - Artigos e Outros Documentos

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