Inhibitory effects of quercetin on guinea-pig ileum contractions

✍ Scribed by J. Gálvez; J. Duarte; F. Sánchez de Medina; J. Jiménez; A. Zarzuelo

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 430 KB
• Volume: 10
• Category: Article
• ISSN: 0951-418X
• DOI: 10.1002/(sici)1099-1573(199602)10:1<66::aid-ptr778>3.0.co;2-b

✦ Synopsis

The inhibitory effect of quercetin on the guinea-pig ileum contractile responses was examined to further clarify its mechanism of action. Quercetin inhibited, from doses of 5 VM, the spontaneous phasic contractions of the guinea-pig ileum, as well as the phasic and tonic components of either acetylcholine-or KCI-elicited contractions, in a dose-dependent way. The former effect was reversible and was unaffected by nicotinic blockade. The tonic component of the contractions was more responsive to quercetin than the phasic component. The inhibition of the tonic contraction was, at least partially, due to the blockade of calcium channels by quercetin, since increasing calcium concentration in the tissue bath reversed the inhibition when the organ was contracted by KCI. Quercetin may also interfere with calcium release from intracellular stores, since it inhibited acetylcholineelicited phasic contraction even in a calcium-free solution. Finally, quercetin shifted the concentration-response curves to carbachol downwards, without modifyng the EDS, of the agonist, whereas the concentration-response curves to CaCI, were shifted downwards and to the right. In conclusion, quercetin inhibits the contractile responses of guinea-pig ileum, decreasing the calcium concentration available for contractile machinery.