title: Different mechanisms of actions of genistein, quercetin on spontaneous contractions of rabbit duodenum.
abstract: Flavonoids are known to relax precontracted intestinal smooth muscle and delay intestinal transit or intestinal peristalsis. The aim of this study was to determine the effects of genistein and quercetin on spontaneous contractions of rabbit duodenum in vitro in an organ bath. Genistein and quercetin (0.1-10µM) reduced the amplitude of spontaneous contractions in the longitudinal and circular smooth muscle of rabbit duodenum, but they did not modify the frequency. Bay K8644 (L-type Ca2+ channel activator), apamin, charybdotoxin, and tetraetylammonium (K+ channel blockers) reverted the inhibition of amplitude of spontaneous contractions induced by genistein in longitudinal and circular smooth muscle. H-89 (protein kinase A inhibitor) antagonized the reduction of the amplitude of spontaneous contractions induced by quercetin in longitudinal and circular smooth muscle of duodenum, while 2,5-dideoxiadenosine (adenylyl cyclase inhibitor) reverted only the reduction of the amplitude in circular smooth muscle. In conclusion, genistein and quercetin reduce the spontaneous contractions in the duodenum by different mechanisms of actions. The effect of genistein would be mediated by Ca2+ and K+ channels, while the effect of quercetin would be mediated by cAMP and protein kinase A.
authors.forename: Diego
authors.initials: D
authors.lastname: Santos-Fagundes
authors.forename: Laura
authors.initials: L
authors.lastname: Grasa
authors.forename: Sergio
authors.initials: S
authors.lastname: Gonzalo
authors.forename: Marta Sofía
authors.initials: MS
authors.lastname: Valero
authors.forename: Marta
authors.initials: M
authors.lastname: Castro
authors.forename: María Pilar
authors.initials: MP
authors.lastname: Arruebo
authors.forename: Miguel Ángel
authors.initials: MÁ
authors.lastname: Plaza
authors.forename: María Divina
authors.initials: MD
authors.lastname: Murillo
mesh_terms: D000818:Animals; D004386:Duodenum / Q000187:drug effects* / Q000378:metabolism; D005765:Gastrointestinal Agents / Q000008:administration & dosage / Q000494:pharmacology*; D019833:Genistein / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects* / Q000502:physiology; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism; D011794:Quercetin / Q000008:administration & dosage / Q000494:pharmacology*; D011817:Rabbits
chemical_list: D005765:Gastrointestinal Agents; D011794:Quercetin; D019833:Genistein