Increase of Cl^- secretion induced by Kampo medicine (Japanese herbal medicine), Sai-rei-to, in Mongolian gerbil middle ear epithelium

Sai-rei-to, a type of Kampo medicine (Japanese herbal medicine), has been shown to be clinically effective in treating patients with otitis media with effusion. The effect of Sai-rei-to on the ion transport of the middle ear surface epithelium cultured from the Mongolian gerbil was investigated by using an Ussing chamber. Application of Sai-rei-to to the mucosal bath but not the serosal bath induced an increase in the short-circuit current (I(SC)) in the basal state. The increase in I(SC) was almost completely inhibited by addition of diphenylamine-2-carboxylic acid but not by amiloride, indicating enhancement of Cl^- secretion. On the basis of the lack of changes in the intracellular Ca²⁺ concentration and a sideness of action, the effect of Sai-rei-to on I(SC) is thought to be a direct and selective activation on the apical Cl^- channel.