Metabolic Factors in Saliva

¹ School of Dental Surgery, University of Liverpool, England

The metabolic activity of the mixed salivary flora is governed to a large extent by one or more co-factors secreted by the parotid gland. The endogenous respiration of washed salivary sediments is reduced to one-tenth the value obtained with whole saliva or with sediment to which saliva supernatant has been added. Endogenous anaerobic glycolysis of the washed sediment is only half that of the whole saliva. In the presence of added glucose, the respiration and glycolysis of the sediments are reduced to one-third and one-half the values obtained with whole saliva. In all cases, the activity of the washed sediments can be restored to that of whole saliva by the addition of saliva supernatant. The co-factor is a relatively small, dialyzable molecule that is heat-stable and does not appear to be an inorganic ion. It is cationic and may be associated with the peptide fraction of saliva. The factor is not replaced by L-glutamic acid, L-glutamine, L-aspartic acid, L-asparagine, DL-serine, phosphoethanolamine, glutathione, -aminobutyric acid, carnitine, choline, pangamic acid, orotic acid, adenosine triphosphate, adenosine diphosphate, or pyrophosphate.