Study of vasorelaxant effect of one pyrone obtained from Aniba panurensis in isolated superior mesenteric artery rat / Estudo do efeito vasorelaxante de uma pirona obtida de Aniba panurensis em artÃria mesentÃrica superior isolada de rato

AUTOR(ES)

Thais Josy Castro Freire de Assis

DATA DE PUBLICAÇÃO

2007

RESUMO

6 - [(E) â styryl] â pyron â 2 - one (pyrone-198) is a natural styrylpyrone isolated from the ethanolic extract of the green fruits of Aniba panurensis (Lauraceae). The pyrones demonstrate a whole spectrum of bioactivity and have been shown to be antifungal, antibiotic, cytotoxic and phytotoxic. The aim of this study is to investigate the effects of this pyrone on isolated rat superior mesenteric rings. Rat superior mesenteric rings (1-2 mm) were suspended by cotton threads for isometric tension recordings in TyrodeÂs solution, 37 ÂC, gassed with 95% O2 and 5% CO2, resting tension 0.75 g. In mesenteric rings pyrone-198 (10-10â10-3 M) induced relaxation of phenylephrine (10 μM) induced tone (EC50=1.1 Â 0.69 x10-5 M) and this effect was unaltered after endothelium removal (EC 50 =1.57 Â 0.35 x 10-5 M). This vasorelaxant effect induced by pyrone-198 was insignificantly altered in the presence of KCl 20 mM In rings pre-contracted with KCl 80 mM pyrone-198 induced relaxant effect (EC50=2,0 Â 0,38 x 10-4 M). Pyrone-198 (10-7â10-4 M) was not able to inhibit the concentration-response curves to CaCl2, however, at a high concentration (10-3 M) it was able to significantly decrease the maximal response. In depolarizing nominally without calcium solution, pyrone-198 (10-8-10-3 M) antagonized transient contractions induced by Phe (10 μM). Pyrone-198 (10-4-10-3 M) slightly antagonized the transient contractions induced by 20 mM caffeine. Sodium orthovanadate (10-5-3 x 10-3 M)- induced contractions were significantly inhibited by higher concentrations of pyrone- 198 (10-4 and 10-3 M). These results suggest that pyrone-198 exerts an endotheliumindependent relaxant effect that seems to involve the calcium influx by voltage operated calcium channels and inhibition of Ca2+ release from intracellular IP3 and ryanodine-sensitive calcium stores. They further suggest that pyrone -198 -induced response seems to be mediated by a pathway related to G-protein coupled receptors signalling

ASSUNTO(S)

fisiologia artÃria mesentÃrica gpcrs mesenteric artery 6 â [(e) â styryl] â pyron â 2 â one rhoa/rho cinase 6 â [(e) â estiril] â piran â 2 â ona (pirona-198) rhoa / rho cinase gpcrs

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