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Here we discuss the development of a novel cell imaging system for the evaluation of smooth muscle cell (SMC) contraction. SMCs were isolated from the circular and longitudinal muscular layers of mouse small intestine by enzymatic digestion. SMCs were stimulated by test agents, thereafter fixed in acrolein. Actin in fixed SMCs was stained with phalloidin and cell length was determined by measuring diameter at the large end of phalloidin-stained strings within the cells. The contractile response was taken as the decrease in the average length of a population of stimulated-SMCs. Various mediators and chemically identified compounds of daikenchuto (DKT), pharmaceutical-grade traditional Japanese prokinetics, were examined. Verification of the integrity of SMC morphology by phalloidin and DAPI staining and semi-automatic measurement of cell length using an imaging analyzer was a reliable method by which to quantify the contractile response. Serotonin, substance P, prostaglandin E2and histamine induced SMC contraction in concentration-dependent manner. Two components of DKT, hydroxy-α-sanshool and hydroxy-β-sanshool, induced contraction of SMCs. We established a novel cell imaging technique to evaluate SMC contractility. This method may facilitate investigation into SMC activity and its role in gastrointestinal motility, and may assist in the discovery of new prokinetic agents.

The effect of Daikenchuto, a traditional herbal medicine, on gastrointestinal hypoperistalsis in postoperative ileus (POI) was investigated. POI was induced by laparotomy with manipulation of the gastrointestine under anesthesia, and gastrointestinal transit was calculated by migration of Evans blue. Daikenchuto(270 – 2,700 mg/kg, p.o.) dose-dependently improved the delayed gastrointestinal transit in POI. This effect of Daikenchutowas partially inhibited by SB204070 (1 mg/kg, s.c.), a 5-hydroxytriptamine4(5-HT4)-receptor antagonist and completely abolished by atropine (1 mg/kg, s.c.), a muscarine-receptor antagonist. Among the constituents of Daikenchuto, the medical herb zanthoxylum fruit (60 mg/kg, p.o.) and maltose syrup (2,400 mg/kg, p.o.) significantly ameliorated the delayed gastrointestinal transit, but ginseng and processed ginger did not affect the gastrointestinal transit in the rat POI. The improvement induced by zanthoxylum fruit was also inhibited by atropine or SB204070. In addition, the high osmotic pressure of the maltose syrup (2400 mg/10 mL per kg) was related to the improvement of delayed gastrointestinal transit. These results demonstrated that Daikenchutoameliorates postoperative hypoperistalsis via cholinergic nerves and 5-HT4receptors and that osmotic pressure also may be involved in this action. Moreover, zanthoxylum fruit and maltose syrup were crucial medical herbs contributing to the ability of Daikenchuto.