The evolutionary path of the epithelial sodium channel δ-subunit in Cetartiodactyla points to a role in sodium sensing.

The epithelial sodium channel (ENaC) plays a key role in osmoregulation in tetrapod vertebrates and is a candidate receptor for salt taste sensation. There are four ENaC subunits (α, β, γ, δ) which form αβγ- or δβγ ENaCs. While αβγ-ENaC is a 'maintenance protein' controlling sodium and potassium homeostasis, δβγ-ENaC might represent a 'stress protein' monitoring high sodium concentrations.