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Type: Artigo de periódico
Title: Phentolamine relaxes human corpus cavernosum by a nonadrenergic mechanism activating ATP-sensitive K+ channel
Author: Silva, LFG
Nascimento, NRF
Fonteles, MC
de Nucci, G
Moraes, ME
Vasconcelos, PRL
Moraes, MO
Abstract: To investigate the pharmacodynamics of phentolamine in human corpus cavernosum (HCC) with special attention to the role of the K+ channels. Strips of HCC precontracted with nonadrenergic stimuli and kept in isometric organ bath immersed in a modified Krebs - Henseleit solution enriched with guanethidine and indomethacine were used in order to study the mechanism of the phentolamine-induced relaxation. Phentolamine caused relaxation (approximate to50%) in HCC strips precontracted with K+ 40 mM. This effect was not blocked by tetrodotoxin ( 1 muM) (54.6 +/- 4.6 vs 48.9 +/- 6.4%) or (atropine ( 10 muM) (52.7 +/- 6.5 vs 58.6 +/- 5.6%). However, this relaxation was significantly attenuated by L-NAME (100 muM) (59.7 +/- 5.8 vs 27.8 +/- 7.1%; P<0.05; n = 8) and ODQ (100 &mu;M) (62.7 +/- 5.1 vs 26.8 +/- 3.9%; P<0.05; n = 8). Charybdotoxin and apamin (K-Ca-channel blockers) did not affect the phentolamine relaxations (54.6 +/- 4.6 vs 59.3 +/- 5.2%). Glibenclamide (100 muM), an inhibitor of K-ATP-channel, caused a significant inhibition (56.7 +/- 6.3 vs 11.3 +/- 2.3%; P<0.05; n = 8) of the phentolamine-induced relaxation. In addition, the association of glibenclamide and L-NAME almost abolished the phentolamine-mediated relaxation (54.6 +/-5.6 vs 5.7 +/- 1.4%; P<0.05; n = 8). The results suggest that phentolamine relaxes HCC by a nonadrenergic noncholinergic mechanism dependent on nitric oxide synthase activity and activation of K-ATP-channel.
Subject: phentolamine
K plus -channels
human corpus cavernosum smooth muscle
erectile dysfunction
Country: Inglaterra
Editor: Nature Publishing Group
Rights: fechado
Identifier DOI: 10.1038/sj.ijir.3901269
Date Issue: 2005
Appears in Collections:Unicamp - Artigos e Outros Documentos

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