Rheological Properties of Human Saliva and Salivary Mucins

Abstract

It is unclear which factors in saliva contribute to its rheological properties such as viscosity and spinnbarkeit. In this study, we investigated relationships between the rheological properties (viscosity and spinnbarkeit) and two salivary mucin (MUC5B and MUC7) levels in saliva. Unstimulated (UWS) and chewing-stimulated (CWS) whole saliva were collected from healthy young adults, and the viscosities and spinnbarkeits were measured. The image densities of MUC5B and MUC7 bands in saliva were measured by Stains-All staining after electrophoresis. Both the viscosity and spinnbarkeit of UWS were significantly higher than those of CWS. The viscosities were correlated positively with the spinnbarkeit in UWS, but not in CWS. Image-density analysis of mucins demonstrated that the viscosities increased with the levels of MUC5B and the spinnbarkeit with the levels of MUC7. These results suggest that MUC5B contributes to viscosity and MUC7 to spinnbarkeit.