The state of calcium and phosphate in saliva.

Abstract

The present knowledge on the state of calcium and phosphate in saliva has been reviewed.Ultrafiltration studies showed that a part of the calcium + magnesium and phosphate in saliva is non‐ultrafiltrable. On an average 9% of the non‐ultrafiltrable phosphate and 23% of the nonultrafiltrable calcium + magnesium was found to be due to precipitation under the conditions of the experiment. Ultrafiltration carried out under 7.5% CO2 in air had a similar effect on the ultrafiltrability of calcium and phosphate as acidification by hydrochloric acid to the same pH. A viscosity reducing enzyme, pronase, had no significant effect. All the phosphate became ultrafiltrable when the pH was reduced below 5.5. Significant reduction in ultrafiltrable calcium and phosphate was observed when the pH was increased from 6.9 to 7.5, but not when this was further increased to 8.0.Gel filtration chromatography carried out through a column of G 100 Sephadex showed that all calcium and phosphorus was associated with relatively low‐molecular material. The UV absorption criteria and the dialyzable nature of the substance indicated that this was probably non‐protein in nature. Further work on the identification of this material is in progress.