Topic zinc application improves mucosal barrier function in experimental TNBS colitis

Background: The aim of this study was to analyze the effect of enterally gi ven zinc and local therapy of zinc on the impaired epithelial barrier funct ion in experimental TNBS colitis in rats. Methods: The following electrophysiological measurements were carried out: 1. Flux measurements for Na+ and mannitol as a parameter of paracellular co lonic permeability, 2. Resistance measurements of the colon, distinguishing between pure epithelial resistance and resistance of the subepithelial tis sue. Results: In TNBS colitis we found a marked increase of both fluxes as a par ameter of enhanced paracellular permeability (factor 3). Further there was a drastic reduction of total resistance, and especially of pure epithelial resistance indicating a massive epithelial barrier defect. In rats treated by zinc per os the increase of paracellular permeability was increased only by a factor of 2, and there was only a moderate decrease of resistance. Th is protective effect was found in a higher degree in rats treated by local (transanal) zinc. Conclusions: These investigations reveal that the protective effect of zinc may be caused by a direct influence on colonic epithelia.