Some chemical characteristics of human minor salivary gland secretions

The minor salivary glands contribute to the composition of whole saliva, but little information has been available about their chemical constituents. Pilocarpine-stimulated labial and palatine secretion from 4 human subjects was investigated by paper and disc electrophoresis, immunochemical analysis, and for content of carbohydrates, amino acids, lipids, hexuronic acids and sulphate. No significant differences were noted between the labial and palatine secretions by any of the methods employed. The minor gland secretions appeared to consist mainly of mucosubstances, possibly with blood group specificity. In addition, three water-soluble components with the characteristics of albumin, alpha-amylase and secretory IgA were seen. The minor gland secretions had an amino acid profile different from those of the major salivary glands and contained higher proportions of carbohydrate. Only one lipid component, with the characteristics of a polar lipid, was seen. Hexuronic acids were not detected in either secretion, whereas both contained sulphate. It would appear that the minor mucous glands contribute to the content of mucosubstances in whole saliva, whereas their content of water-soluble material is negligible in this respect.