The epithelial sodium channel (short: ENaC, also: sodium channel non-neuronal 1 (SCNN1) or amiloride sensitive sodium channel (ASSC)) is a membrane-bound ion-channel that is permeable for Li<sup>+</sup>-ions, protons and especially Na<sup>+</sup>-ions. It is a constitutively active ion-channel. It is arguably the most selective ion channel.
The apical membrane of many tight epithelia contains sodium channels that are primarily characterised by their high affinity to the diuretic blocker amiloride. In vertebrates, the channels control reabsorption of sodium in kidney, colon, lungand sweat glands; they also play a role in taste perception.