Pharmacological differences between Liu-Jun-Zi-Tang, a traditional Chinese herbal medicine, and domperidone on isolated guinea-pig ileum

The different characteristics of Liu-Jun-Zi-Tang, a spray-dried powdered extract from 8 Chinese herbs, and domperidone, a D2 antagonist, both of which are used clinically for the treatment of gastritis, were validated in isolated guinea pig ileal longitudinal muscle. Liu-Jun-Zi-Tang at 0.05 mg/ml did not affect the twitch response by electrical field stimulation, but it concentration-dependently inhibited the twitch response at concentrations of 0.1 and 1.0 mg/ml, and maximum inhibition occurred 5 min after application of Liu-Jun-Zi-Tang. In the presence of Liu-Jun-Zi-Tang, the concentration-response curve for ACh-contraction showed inhibition in a non-competitive manner, which is the same as domperidone. In the presence of Liu-Jun-Zi-Tang (1.0 mg/ml), ACh (10(-7) M)-, histamine (5x10(-7) M)- and barium chloride (10(-4) M)-induced basal contractions were inhibited by 24, 19 and 54 %, respectively. On the other hand, in the presence of domperidone (2x10(-5) M), ACh- and barium chloride-induced basal contractions were inhibited by 28 and 63%, respectively, similar to that in the presence of Liu-Jun-Zi-Tang. However, the inhibition of histamine-induced contraction in the presence of domperidone was significantly increased (81%) compared with that in the presence of Liu-Jun-Zi-Tang. These findings suggest that Liu-Jun-Zi-Tang has milder effects on histamine-induced disorders than domperidone. In other words, domperidone has a more potent effect on histamine-induced disorders.