Phosphate Equilibrium Between Plasma and Saliva. ∗

Abstract

Incidental to a trial of radioactive phosphorus in the therapy of carcinomatous metastases to bone we have been able, through the courtesy of Dr. George E. Fahr, to make some observations as to the secretion of radiophosphorus in the saliva. The results have some bearing on the interpretation of the studies by Sognnaes and Volker 1 and Barnum and Armstrong 2 dealing with the uptake of radioactive phosphorus by dental enamel from the saliva. The subject was a woman, aged 52, with advanced carcinoma of the breast, and the observations were made 19 days before death when the patient was not cachectic. Four grams of sodium phosphate, containing 42,000,000 Geiger-Mueller counts of radioactive phosphorus, dissolved in 100 cc of water were administered by stomach tube.

One hour following the administration of the radioactive salt a sample of saliva, stimulated by the chewing of paraffin, was collected over a 26-minute period. A second saliva sample was collected 3 hours after administration of the salt and, midway in this collection, a sample of venous blood was obtained. The final saliva sample was taken 24 hours after the administration. The urine was collected during the 24 hours following the administration of the active phosphate.

The saliva samples were centrifuged to remove the mucus, treated with equal volumes of 14% trichloracetic acid and centrifuged again. The supernatant fluid was used for the determination of radiophos-phorus and total phosphorus. The blood was collected in an oxalate tube and centrifuged. The proteins were removed from the plasma by addition of trichloracetic acid to 5% concentration and the supernatant fluid was used for the active phosphorus and chemical phosphorus determinations. The radioactivity measurements were made upon basic calcium phosphate precipitates prepared under identical conditions by a technic developed in this laboratory.