Changes in protein and glycoprotein concentrations in human submaxillary saliva under various stimulatory conditions

Abstract

The concentrations of protein and protein-bound carbohydrates in human submaxillary saliva depended on salivary flow rate and not on the specific type of gustatory stimulus. “Unstimulated” saliva had the highest concentration of protein-bound carbohydrates. Low flow rates were associated with the lowest concentrations of protein and protein-bound carbohydrates, and as flow rate was increased, there was an accompanying increase in the concentrations of these substances. The concentrations of protein-bound carbohydrates were highly variable in “unstimulated” saliva. Stimulated saliva was relatively more predictable in composition. Protein concentration averaged 122 ± 76 (S.D.) mg%; however, the change in concentration from the lowest to the highest value recorded represented an increase of 1600%. Similarly, the concentration of protein-bound carbohydrates varied as much as 450% in the case of galactose. Average concentrations (μM) for protein-bound carbohydrates were: galactose, 395 ± 235; hexosamine, 290 ± 169; sialic acid, 151 ± 83; fucose, 160 ± 108. Secretors of blood group substances had concentrations of protein-bound carbohydrates higher than non-secretors, except for sialic acid concentration which was similar for the two groups. The sialic acid/fucose ratio for secretors was 0.64 ± 0.12 and did not vary with flow rate. The ratio for non-secretors was 1.40 ± 0.35 and rose with increasing flow rate.