Inhibitory Effects of Magnolol on Distal Colon of Guinea Pig in Vitro(Miscellaneous)

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The influence of plant product magnolol (0-100μM) on the contractile activity of isolated colonic muscle strips in guinea pig and related mechanism were investigated. Magnolol did not affect the base tone of colon muscle strips, but it dose-dependently inhibited 40 mM KCl-, 1μM carbachol (CCh)- and 10μM serotonin (5-HT)-induced contractions at concentrations higher than 10μM. And also, magnolol inhibited the 5-HT- or CCh-induced muscle contraction in calcium-free buffer. Furthermore, magnolol inhibited the KCl-induced contraction under the condition of procaine. In addition, inhibition rate of nifedipine plus magnolol on muscle strips was lower than that of nifedipine alone. Moreover, magnolol dose-dependently decreased the velocity of pellet propulsion in the concentration range of 0.1-10μM, and totally inhibited pellet propulsion at the concentration higher than 30μM. Thus, it can be concluded that magnolol may 1) block receptor-operated cation channels and the voltage dependent Ca^<2+> channel, and 2) inhibit calcium release from the sarcolemmal membrane (SR) through blocking InsP_3-sensitive and ryanodine-sensitive pathways. This explains, at least partially, that Cortex magnoliae officinalis exerts therapeutic effects on gastrointestinal disease through relaxation of GI tract smooth muscles.
社団法人日本薬学会の論文
2006-04-01