| Institution: | 1. School of Chinese Medicine, Hong Kong Baptist University, Hong Kong Special Administrative Region;2. Guangzhou Research Institute of Snake Venom, Guangzhou Medical University, Guangzhou, China;3. Institute of Vascular Medicine, Li ka Shing Institute of Health Sciences and School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region;4. Shanghai University of Traditional Chinese Medicine, Shanghai, China;5. The Chinese University of Hong Kong, Hong Kong Special Administrative Region;1. Department of Physiology, Saga Medical School, 5-1-1 Nabeshima, 849-8501, Saga, Japan;2. Department of Gastroenterology, The First Affiliated Hospital of Nanchang University, 330006, Nanchang, China;1. Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran;2. Neuroscience Research Center and Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran;3. Neurophysiology Unit, GIGA Neurosciences, University of Liege, Liege, Belgium;1. Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing 210029, China;2. The First Affiliated Hospital of Xinxiang Medical University, Weihui 453100, China |
| 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 Ca2+ 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 N?-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 Ca2+ currents. The present results suggest that magnolol inhibits colonic smooth muscle contraction through downregulating L-type Ca2+ channel activity. |
