Excretion of sodium, potassium, chloride and carbon dioxide in human parotid saliva.

H EIDENHAIN (I) first demonstrated that the concentration of inorganic salts in the submaxillary saliva of dogs varies in proportion to the secretory rate. Gregersen and Ingalls (2) showed that the concentration of sodium increases with increasing rates of secretion, whereas the concentration of potassium is independent of salivary flow. This finding has been confirmed by later investigators working on submaxillary saliva of various animals (3-5) and on human mixed saliva (6). In the present experiments the concentrations of sodium, potassium, bicarbonate, and chloride were measured simultaneously in human parotid saliva following stimulation of the secretion by the subcutaneous injection of beta-methyl-acetylcholine hydrochloride. The results obtained on the relative rates of excretion of potassium and sodium by the parotid gland are compatible with the hypothesis that both cations are brought into a precursor solution at a rate which varies in direct proportion to the rate of salivary flow, and that sodium is withdrawn from this precursor solution by a process of reabsorption which is limited by a maximal capacity.