Lysolecithin affects the viscosity, permeability, and peptic susceptibility of gastric mucin

The effect of lysolecithin and lecithin on gastric mucin viscosity, permeability to hydrogen ion, and degradation by pepsin was investigated. Preincubation with lysolecithin produced a marked decrease in the glycoprotein viscosity. This decrease was concentration-dependent and at 10 mM lysolecithin reached a value of 74%. A 25% increase in mucin viscosity was obtained with 10 mM lecithin. Permeability measurements showed that 10 mM lecithin increased the retardation ability of the glycoprotein to hydrogen ion by 11%, whereas a 12% decrease in the retardation capacity of the glycoprotein was obtained with 10 mM lysolecithin. The results of peptic activity assay indicated that whereas lecithin had no effect on the rate of mucin proteolysis, the lysolecithin exerted significant (75%) stimulatory effect. The results suggest that lysolecithin in the stomach weakens the integrity of the protective mucus layer by promoting peptic degradation, reducing the ability to resist acid penetration, and decreasing viscosity of its mucin component.