Viscoelastic properties of airway mucus.

Mucus is a viscoelastic gel that exhibits both liquid-like and solid-like properties. Viscoelasticity can be determined in both transient and dynamic experiments, which give in principle the same information; the latter, however, offer a simpler interpretation. The principal determinant of mucus viscoelasticity appears to be mucin content; pH, added salts, serum proteins, and DNA have also been found to affect mucus viscoelasticity. However, agreement between studies, even equalitative, is far from complete. Acute pharmacologic interventions can significantly alter airway mucus viscoelasticity. The mechanism by which the changes occur remains to be explored, but alterations in epithelial ion transport and membrane permeability to protein offer rational explanations for the observations.