Alteration of the Physical Pathways Through the Gastric Mucosa by Sodium Taurocholate

Abstract

The effect of sodium taurocholate (Tch) on gastric mucosal permeability was investigated using an in vitro preparation of rabbit fundic gastric mucosa mounted in an Ussing chamber, and perfused with a physiological solution at 37°C. The permeability was measured by the mucosal to serosal flux of [14C]erythritol, a water-soluble, non-lipidsoluble molecule. The flux rate of erythritol in normal tissue was 1.85 ± 0.25 pmoles per cm2 per sec. and was increased by 20 mM Tch in the mucosal solution at pH 7.0 and pH 3.0, to 5.46 ± 0.54, and 25.48 ± 4.71 pmoles per cm2 per sec, respectively, after 1 hr, demonstrating a pH-dependent effect. At pH 3.0, Tch in the mucosal solution at doses of 2.5, 5, and 10 mM increased the mucosal to serosal flux rate to 3.98 ± 1.29, 5.81 ± 1.37, and 13.52 ± 2.31 pmoles per cm2 per sec, respectively, after 1 hr, demonstrating a dose-related effect. There was no statistical difference between the mucosal to serosal flux of erythritol with 20 mM Tch in the mucosal or serosal solutions. The fluxes of [14C]mannitol and [14C]lactose were altered in a similar direction by Tch, but the absolute flux of these substances was less than that of erythritol because of the larger size of the molecule. It is suggested that Tch causes an increase in permeability of the gastric mucosa through water-filled channels, which may be responsible for the increased transmucosal flux of hydrogen and sodium ions caused by bile salts.