ELECTROLYTE TRANSPORTS INVOLVED IN THE FORMATION OF SALIVA

Abstract

The fluid formation in the salivary glands occurs in the acini. The acinar secretory process is an isotonic water transport, in which the main active step is a sodium transport from the intracellular to the intercellular space, which probably provides the structural basis for the coupling between the active solute transport and the passive transport of water, according to the Diamond hypothesis. Sodium enters along the basal cell membrane, down an electrochemical gradient, as a result of an acetylcholine-induced enhanced permeability of the basal cell membrane to potassium and sodium that also changes the potential difference across this membrane. The result is the formation of an isotonic, high sodium and low potassium fluid that is modified in the duct system, mainly in the region of the striated ducts, by reabsorption of sodium chloride in excess of water and in some glands by secretion of potassium bicarbonate. These transport processes are under the influence of the autonomic nerve system as is the acinar secretory process.