Amiloride-sensitive Na+ current in the granular duct cells of mouse mandibular glands

Whole-cell patch clamp studies on dispersed cells from the intralobular ducts of mouse mandibular glands reveal the presence of an amiloride-sensitive Na(+)-selective conductance that is not found in the cells of the secretory endpieces. Since studies on ripped-off outside-out patches from the basolateral membranes of isolated intralobular ducts show that the membrane conductance is not altered by amiloride, it can be inferred that the Na+ conductance seen in whole-cell experiments is located in the luminal membrane. These studies thus provide evidence for the presence of a luminal Na+ conductance in salivary ducts and indicate that intralobular and extralobular ducts may handle Na+ in a similar manner.