Functional expression of the epithelial sodium channel δ-subunit in human respiratory epithelial cells

Abstract

Mammalian amiloride-sensitive epithelial Na+ channel (ENaC) can be composed by different combinations of four homologous subunits, α, β, γ and δ. The canonical αβγ- ENaC, abundantly expressed in Na+ absorbing epithelia, is thoroughly investigated and well known for its crucial role in Na+ homoeostasis. Via aldosterone-controlled Na+ reuptake in the kidney, ENaC regulates blood volume and pressure. In the lung, it facilitates the maintenance of alveolar lining fluid layer and efficient gas exchange. Delta-ENaC, mainly expressed in non-epithelial tissues, has recently been described in human airway epithelia. Its physiological role, however, remains largely hypothetical and is primarily based on the expression data as well as the biophysical characteristics of the heterologously expressed protein.