College of Veterinary Medicine, Kyungpook National University, Daegu 702-707, Korea.
Arch Pharm Res. 2009 Nov;32(11):1613-20. doi: 10.1007/s12272-009-2115-z.
Using rat gastrointestinal (GI) strips, this study investigated the stimulatory effects of methylisogermabullone (MIGB) purified from radish on the spontaneous contractility of GI smooth muscles and pharmacological mechanisms involved in the MIGB-induced GI contraction. MIGB at 30 microM differently regulated the tone and amplitude of spontaneous GI contractility according to the region (fundus through distal colon) and orientation (longitudinal and circular) of smooth muscles: a significant increase in both tone and amplitude of spontaneous contraction in the ileum longitudinal and distal colon circular muscles and in amplitude only in the fundus, jejunum and distal colon longitudinal muscles. Pretreatment of ileum longitudinal muscles with atropine (0.5 microM) or 4-DAMP (0.5 microM) significantly inhibited the acetylcholine (ACh, 1 microM)- and MIGB (30 microM)-stimulated contraction, and methoctramine (0.5 microM) also obviously reduced the tone and amplitude increased by ACh and MIGB, respectively. In the presence of methysergide (1 microM), pretreatment of ileum longitudinal muscles with both ondansetron (0.1 microM) and GR113808 (0.1 microM) significantly inhibited the contraction stimulated by 5-HT (10 microM), but not by MIGB. Taken together, it is concluded that MIGB differently regulates the spontaneous contractility (tone and/or amplitude) of GI segments according to the region of gut and orientation of smooth muscles, and these contractile responses of GI tracts to MIGB are likely mediated, at least, by activation of acetylcholinergic M2 and M3 receptors.
本研究使用大鼠胃肠道（GI）条带，探讨了从萝卜中纯化的甲基异戈曼宁（MIGB）对 GI 平滑肌自发性收缩的刺激作用以及涉及 MIGB 诱导的 GI 收缩的药理学机制。30μM 的 MIGB 根据 GI 区域（从胃底到远端结肠）和平滑肌方向（纵向和环形）不同地调节自发性 GI 收缩的张力和幅度：在回肠纵向和远端结肠环形肌肉中，自发性收缩的张力和幅度均显著增加，而在胃底、空肠和远端结肠纵向肌肉中仅增加幅度。在回肠纵向肌肉中预先用阿托品（0.5μM）或 4-DAMP（0.5μM）处理可显著抑制乙酰胆碱（ACh，1μM）和 MIGB（30μM）刺激的收缩，而美索他胺（0.5μM）也明显降低了 ACh 和 MIGB 分别增加的张力和幅度。在美西麦角（1μM）存在的情况下，在回肠纵向肌肉中预先用昂丹司琼（0.1μM）和 GR113808（0.1μM）处理可显著抑制 5-HT（10μM）刺激的收缩，但对 MIGB 没有抑制作用。综上所述，MIGB 根据肠道区域和平滑肌方向不同地调节 GI 段的自发性收缩（张力和/或幅度），并且 GI 对 MIGB 的这些收缩反应可能至少通过激活乙酰胆碱能 M2 和 M3 受体来介导。
