Sodium permeable non-voltage-sensitive ion channel inhibited by the diuretic amiloride. Mediates the electrodiffusion of the luminal sodium (and water, which follows osmotically) through the apical membrane of epithelial cells. Plays an essential role in electrolyte and blood pressure homeostasis, but also in airway surface liquid homeostasis, which is important for proper clearance of mucus. Heterotrimer containing an alpha/SCNN1A, a beta/SCNN1B and a gamma/SCNN1G subunit. An additional delta/SCNN1D subunit exists only in some organisms and can replace the alpha/SCNN1A subunit to form an alternative channel with specific properties. Apical membrane of epithelial cells. Strongly expressed in gill, kidney and rectum and more weakly in brain, eye, liver and muscle. Belongs to the amiloride-sensitive sodium channel (TC 1.A.6) family. SCNN1B subfamily.