title: Inhibitory Effects of Quercetin on Muscle-type of Nicotinic Acetylcholine Receptor-Mediated Ion Currents Expressed in Xenopus Oocytes.
abstract: The flavonoid quercetin is a low molecular weight compound generally found in apple, gingko, tomato, onion and other red-colored fruits and vegetables. Like other flavonoids, quercetin has diverse pharmacological actions. However, relatively little is known about the influence of quercetin effects in the regulation of ligand-gated ion channels. Previously, we reported that quercetin regulates subsets of nicotinic acetylcholine receptors such as α3β4, α7 and α9α10. Presently, we investigated the effects of quercetin on muscle-type of nicotinic acetylcholine receptor channel activity expressed in Xenopus oocytes after injection of cRNA encoding human fetal or adult muscle-type of nicotinic acetylcholine receptor subunits. Acetylcholine treatment elicited an inward peak current (I(ACh)) in oocytes expressing both muscle-type of nicotinic acetylcholine receptors and co-treatment of quercetin with acetylcholine inhibited I(ACh). Pre-treatment of quercetin further inhibited I(ACh) in oocytes expressing adult and fetal muscle-type nicotinic acetylcholine receptors. The inhibition of I(ACh) by quercetin was reversible and concentration-dependent. The IC(50) of quercetin was 18.9±1.2 µM in oocytes expressing adult muscle-type nicotinic acetylcholine receptor. The inhibition of I(ACh) by quercetin was voltage-independent and non-competitive. These results indicate that quercetin might regulate human muscle-type nicotinic acetylcholine receptor channel activity and that quercetin-mediated regulation of muscle-type nicotinic acetylcholine receptor might be coupled to regulation of neuromuscular junction activity.
authors: Department of Physiology, College of Veterinary Medicine and Bio/Molecular Informatics Center, Konkuk University, Seoul 143-701, Korea.
authors: Byung-Hwan
authors: BH
authors: Lee
authors: Tae-Joon
authors: TJ
authors: Shin
authors: Sung-Hee
authors: SH
authors: Hwang
authors: Sun-Hye
authors: SH
authors: Choi
authors: Jiyeon
authors: J
authors: Kang
authors: Hyeon-Joong
authors: HJ
authors: Kim
authors: Chan-Woo
authors: CW
authors: Park
authors: Soo-Han
authors: SH
authors: Lee
authors: Seung-Yeol
authors: SY
authors: Nah