Electrolyte and water transport by salivary gland slices

¹ Department of Physiology, University of Alabama Medical College and School of Dentistry, Birmingham, Alabama

Net movements of water, electrolytes, and total solids were investigated in slices of rat submaxillary gland to delineate transport mechanisms of possible significance in normal salivary secretion. Gland slices gained weight in oxygenated Krebs-Ringer-phosphate from greater influx of water than efflux of solids. Most of the water gained entered cells. Tissue and cell K decreased, while Na and Cl increased. In KRP-N₂, slices gained even more weight than in O₂, from increased water influx; here more of the water remained in extracellular space. Gain of tissue Cl was comparable but Na gain and K loss by tissue and cells were greater than in oxygenated medium. Readmission of O₂ after N₂ incubation resulted in weight loss from further loss of solids with no change in total tissue water; however, a redistribution of water in the tissue, involving expansion of intracellular at the expense of extracellular space, was observed. Tissue and cell Cl further increased; K was reaccumulated, and Na left the cells. Net Na efflux and K influx against chemical and electrical gradients occurred consistently. Submaxillary gland cells can extrude Na and accumulate K by active transport.