Control of Na+ transport in salivary duct epithelial cells by cytosolic Cl- and Na+

• Published in: European journal of morphology Vol. 36 Suppl; p. 67
• Main Authors: Cook, D I, Dinudom, A, Komwatana, P, Young, J A
• Format: Journal Article
• Language: English
• Published: England 01-08-1998
• Subjects: Animals; Biological Transport - physiology; Chlorides - metabolism; Cytosol - metabolism; Epithelial Cells - metabolism; Mice; Salivary Ducts - cytology; Salivary Ducts - metabolism; Sodium - metabolism; Submandibular Gland - cytology; Submandibular Gland - metabolism
• ISSN: 0924-3860

The duct cells of the mandibular glands of mice (and many other mammalian salivary glands) absorb NaCl from an isotonic, Na+-rich primary saliva, formed by the gland's secretory endpieces, utilising an amiloride-sensitive Na+ channel in the apical (luminal) domain of the plasma membranes. The present study focuses on the mechanisms whereby the apical membrane Na+ conductance is controlled so that the rate of Na+ influx from lumen to cytosol via the Na+ channels is matched to the rate of Na+ extrusion from cytosol to interstitium via the basolateral Na+-K+-ATPase (so called homocellular regulation or epithelial cross-talk). Our results show that the apical membrane Na+ conductance is not controlled by a sensor of extracellular (luminal) Na+, as has been previously believed, but by sensors of cytosolic Na+ and Cl- which down-regulate the Na+ channels when the cytosolic concentration of either ion increases. These effects of cytosolic Na+ and Cl- are mediated, respectively, by G proteins of the Gi and Go subclasses.