[Pharmacological studies on antidiarrheal effects of a preparation containing berberine and geranii herba]

We studied the effects of a preparation containing Berberine and Geranii Herba (BGH) on different diarrheal models of mice and the contractions of isolated guinea pig intestinal smooth muscle, comparing these effects with those of a preparation containing creosote (CSG) and loperamide (LP). BGH, as well as CSG and LP, significantly inhibited the diarrhea induced by castor oil or BaCl2, but not the diarrhea induced by pilocarpine or serotonin. BGH inhibited ACh-, Ba(2+)- or electrical stimulation (ES)-induced contraction of the ileum or colon at concentrations from 10(-6) to 10(-4) g/ml. On the other hand, the inhibitory effect of CSG on the ES-induced contraction was about one hundred times stronger than that on ACh- or Ba(2+)-induced contraction. The order of the inhibitory potency of LP on contractions of the ileum in this test was ES > Ba2+ > ACh, and LP showed stronger inhibition against the contraction of the ileum than that of the colon. These results suggest that BGH exerts its antidiarrheal action by inhibiting intestinal movement, and the mechanism of action of BGH may differ from those of CSG or LP.