Effect of Severe Anoxia on the Permeability of Gastric Mucosa 1

Summary

The effect of severe anoxia produced by gassing with 100% nitrogen on gastric mucosal permeability and hydrogen ion back diffusion was investigated using an in vitro preparation of rabbit fundic gastric mucosa mounted in an Ussing chamber. Permeability was estimated by determination of the flux of the water soluble, nonlipid soluble molecule erythritol from the mucosal to serosal solution. The flux rate across normal tissue was 2.80 ± 0.41 pmoles/cm²/sec, and rose to 3.32 ± 0.57 pmoles/cm²/sec after 2 hr of severe anoxia. Hydrogen ion back diffusion was measured by determining with a pH stat the amount of hydrogen ion required to maintain the [H+] of the mucosal solution at 0.1, 1.0, 2.0 and 3.2 mEq/L in both normal and anoxic tissues. One hour of anoxia increased the back diffusion of H+, but the changes only became statistically significant at all pH values after 1.5 hr. Anoxia did however cause an immediate fall in potential difference to zero, and a rise in resistance which after 30 min fell progressively to preanoxic levels. Anoxia produces a small increase in gastric mucosal permeability, an effect which may be enhanced by other factors.