Relaxamento do músculo liso traqueal de rato pelo eugenol. / Relaxation of rat tracheal smooth muscle by eugenol.

AUTOR(ES)

Felipe Crescêncio Lima

FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

27/02/2009

RESUMO

Eugenol, a phenol monoterpenoid, is the main component of clove oil. This study aims to evaluate the relaxation of tracheal smooth muscle of rat by eugenol and the mechanisms underlying these effects. We used preparations of trachea of male Wistar rats maintained in aerated modified Tyrode to record isometric muscle contractions. Increasing and cumulative concentrations (1 to 2000 μM) of eugenol did not affect the basal tone, however relaxed in a concentration-dependent contractions induced by KCl (80 mM) (EC50: 597.03 60.6 mM) and by 1 μM of carbachol (EC50: 571.31 148.80 μM). The presence of 10 μM of capsazepine or 2 μM of indomethacin did not significantly alter the EC50 of the contraction induced by pharmachomecnical coupling, however in the contractions induced by electromechanical coupling, the capsazepine reduced the EC50 to 153.03 28.52 μM. Eugenol was also able to inhibit contractions induced by electrical field stimulation (EFS) (EC50: 842.3 52.7 μM) and nor the presence of indomethacin, neither of montelukast (10 μM) significantly altered these EC50. This inhibition was also significant in concentration-response curve of acetylcholine in the presence of 1 mM of eugenol. In Ca2+-free medium containing 0,2 mM EGTA, 2 mM eugenol inhibited completely the contraction induced by ACh. In the presence or absence of 1 μM thapsigargin, eugenol (300 to 2000 μM) significantly relaxed the contractions induced by phorbol dibutyrate (DBF). The potency of eugenol for relaxation of contractions was similar in all mechanisms except the of the mechanism activated by voltage-dependent Ca2+ channel, which was more potent than dependent mechanisms of receptor-operated channels. In conclusion, the relaxation induced by eugenol may be mediated by several mechanisms with the same potency, except for that dependent of voltage-operated Ca2+ channel, or through a direct interaction with a later stage of contraction and common to all mechanisms.

ASSUNTO(S)

acoplamento excitação-contração eugenol estimulação de campo elétrico miorrelaxante músculo liso traquéia isolada fisiologia excitation-contraction coupling eugenol electrical field stimulation myorelaxing smooth muscle trachea

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