The effect of sulphydryl compounds and cross linking agents on the viscous and viscoelastic properties of mucus 1

In order to understand more about the rheological properties of mucoid secretions and the mechanisms by which they are thickened or thinned by drugs, a model system based on hog gastric mucin has been employed. The consistency of a 10 per cent dispersion of mucin in tris buffer is little affected by changes in pH, ionic strength and the addition of specific ions such as Ca²⁺. The effect of mucolytic sulphydryl and proteolytic compounds has been followed using continuous shear viscometry and a new stress relaxation method. Other agents (surface active agent, and urea) have a similar effect to water. The model can be thickened by the addition of a disodium tetraborate, a cross-linking agent.