Berberine inhibits ion transport in human colonic epithelia

The effects of berberine on ion transport in both human colonic mucosal epi thelia and an intestinal epithelial cell line (T84) were examined. Berberin e (concentration range 0-500 mu M) reduced both basal and stimulated ion tr ansport responses in human colonic mucosae in a manner which was non-specif ic for Ca2+- or cAMP-mediated signals. Similarly, in cultured intestinal ep ithelial monolayers, berberine inhibited Ca2+- and cAMP-mediated responses indicating an inhibitory activity directly at the level of the epithelium r ather than an indirect effect through other mucosal element(s). Berberine d id not alter the rate of generation of cAMP by adenylyl cyclase or the acti vity of protein kinase A, the effector enzyme of the cAMP pathway. Berberin e inhibited carbachol-stimulated Rb-86(+) efflux from T84 monolayers. Berbe rine also inhibited K+ conductance in apically-permeabilised re-sected muco sae. These results indicate i) that berberine exerts an anti-secretory acti on directly upon epithelial cells and ii) the mechanism of action may be at the level of blockade of K+ channels. (C) 1999 Elsevier Science B.V. All r ights reserved.