Restriction of Hydrogen and Sodium Ion Diffusion in Porcine Gastric Mucin: A Concentration Dependent Phenomenon

Abstract

Gastric mucin has long been thought of as having a protective role against the high levels of acidity that the mucosa are often exposed to. With the advent of the concept of an ‘unstirred layer’ next to all membranes,mucin has been envisaged as providing a structural framework for maintaining and extending an external unstirred layer. Such an unstirred layer within the mucus is thought to reduce access to the mucosa by increasing the mean diffusion path length (1) and the possible ability of mucus to retard hydrogen ion access by restricting the free diffusion is often discounted (2) Since mucus is an exceptionally viscous substance,a restriction of the diffusion process might be expected,as predicted by the Stokes-Einstein equation (3).