Effect of "Shugan Decoction" on Colon Longitudinal Smooth Muscle Tension in Rats with Diarrhea-predominant Irritable Bowel Syndrome in vitro

Objective: To investigate the possible mechanism of Shugan Decoction in treating diarrhea-predominant irritable bowel syndrome(IBS).Methods: Sixty rats were randomly divided into normal group and model group.All colon intestinal muscle specimens were produced by experimental methods and placed it in the baths,connected to a tension transducer,then a fixed concentration of acetylcholine(Ach) was added into the baths.According to the different drugs added,intestinal muscle specimens were divided into control group and Shugan Decoction group.Results: Shugan Decoction could antagonize the intestinal muscle excitability induced by Ach and had inhibitory effect on rat intestinal muscle tension both in normal group and model group.At the same concentration of Shugan Decoction,the change of muscle tension was more significantly in model group than in normal group.Conclusion: Shugan Decoction can treat diarrhea-predominant IBS by inhibiting the contraction of intestinal muscle,reducing the tension of intestinal muscle,and suppressing M-cholinergic receptors.