Is gastro-intestinal mucus an ion-selective barrier?
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.
Guth
D
D
Department of Physiology, School of Veterinary Medicine, Federal Republic of Germany.
von Engelhardt
W
W
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
D007477:Ions