title: Is gastro-intestinal mucus an ion-selective barrier?
abstract: The mucus layer at the epithelial surface seems to be responsible for the formation of a microclimate in which the concentrations of H+, K+, Na+, and Cl- are rather constant. It is possible that this is not due simply to an unstirred layer effect, but also to a higher diffusion resistance of mucus. Flux measurements revealed that sodium and potassium permeabilities in mucus are 50% lower than those in saline. Dilution and biionic diffusion potentials indicated a higher relative permeability of mucus for sodium and potassium than for chloride. Thus mucus represents a diffusion barrier, slightly more permeable for cations than for anions.
authors.affiliation: Department of Physiology, School of Veterinary Medicine, Federal Republic of Germany.
authors.forename: D
authors.initials: D
authors.lastname: Guth
authors.forename: W
authors.initials: W
authors.lastname: von Engelhardt
mesh_terms: D000818:Animals; D004058:Diffusion; D004594:Electrophysiology; D005753:Gastric Mucosa / Q000502:physiology*; D007413:Intestinal Mucosa / Q000502:physiology*; D007477:Ions; D009093:Mucus / Q000502:physiology*; D012756:Sheep; D013552:Swine
chemical_list: D007477:Ions