THE SITES OF TRANSFER OF SODIUM, POTASSIUM, AND IODIDE IN THE PAROTID DUCT SYSTEM OF THE DOG

Rapid intra-arterial injections of radioactive iodide, sodium, and potassium have been made into the carotid artery while the parotid gland was secreting saliva at a steady rate. All three ions appeared in the saliva within a few seconds with iodide lagging slightly behind sodium and potassium. The curve for potassium was several times as long as those for sodium and iodide. With intravenous injections of the isotopes, after sufficient time had been allowed for equilibration between the blood and the parotid gland, there was an initial transient concentration of all three ions when secretion started after a rest period. The transient concentrations for sodium and potassium appeared slightly ahead of that for iodide. Potassium showed a clear second phase in its rest transient concentration.It is concluded that all three ions are able to cross the salivary duct epithelium and enter the saliva. Evidence for active transfer of potassium into the salivary duct lumen is presented.