title: Magnolol inhibits colonic motility through down-regulation of voltage-sensitive L-type Ca2+ channels of colonic smooth muscle cells in rats.
abstract: This study aimed to investigate the effect of magnolol (5,5'-diallyl-2,2'-biphenyldiol) on contraction in distal colonic segments of rats and the underlying mechanisms. Colonic segments were mounted in organ baths for isometric force measurement. Whole-cell voltage-sensitive L-type Ca(2+) currents were recorded on isolated single colonic smooth muscle cells using patch-clamp technique. The spontaneous contractions and acetylcholine (ACh)- and Bay K 8644-induced contractions were inhibited by magnolol (3-100 μM). In the presence of Bay K8644 (100 nM), magnolol (10-100 μM) inhibited the contraction induced by 10 μM ACh. By contrast, tetrodotoxin (100 nM) and Nώ-nitro-L-arginine methyl ester (L-NAME 100 μM) did not change the inhibitory effect of magnolol (10 μM). In addition, magnolol (3-100 μM) inhibited the L-type Ca(2+) currents. The present results suggest that magnolol inhibits colonic smooth muscle contraction through downregulating L-type Ca(2+) channel activity.
authors: School of Chinese Medicine, Hong Kong Baptist University, Hong Kong Special Administrative Region; Guangzhou Research Institute of Snake Venom, Guangzhou Medical University, Guangzhou, China.
authors: Man
authors: M
authors: Zhang
authors: Kai-Hong
authors: KH
authors: Zang
authors: Jia-Lie
authors: JL
authors: Luo
authors: Fung-Ping
authors: FP
authors: Leung
authors: Yu
authors: Y
authors: Huang
authors: Cheng-Yuan
authors: CY
authors: Lin
authors: Zhi-Jun
authors: ZJ
authors: Yang
authors: Ai-Ping
authors: AP
authors: Lu
authors: Xu-Dong
authors: XD
authors: Tang
authors: Hong-Xi
authors: HX
authors: Xu
authors: Joseph Jao-yiu
authors: JJ
authors: Sung
authors: Zhao-Xiang
authors: ZX
authors: Bian
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001713:Biphenyl Compounds / Q000494:pharmacology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000378:metabolism*; D003106:Colon / Q000187:drug effects* / Q000378:metabolism; D015536:Down-Regulation; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D017705:Lignans / Q000494:pharmacology*; D031566:Magnolia / Q000737:chemistry*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D001713:Biphenyl Compounds; D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D004365:Drugs, Chinese Herbal; D017705:Lignans; C005498:magnolol; D000109:Acetylcholine
keywords: 5-HT; ACh; CCh; Colonic motility; ENS; L-type Ca(2+) channels; Magnolia officinalis; Magnolol; N(ώ)-nitro-l-arginine methyl ester; NO; Smooth muscle cells; TTX; VGCC; acetylcholine; carbachol; enteric nervous system; l-NAME; nitric oxide; serotonin; tetrodotoxin; voltage-sensitive Ca(2+) channels