Epithelial sodium channel subunit alpha (αENaC)

The epithelial sodium channel subunit alpha (αENaC) is one of the three principal subunits (α, β, γ) forming the heterotrimeric, amiloride-sensitive epithelial sodium channel (ENaC), primarily expressed in the apical membranes of epithelial cells in kidney, colon, lung, and exocrine glands. It mediates the electrodiffusion of sodium ions from the extracellular space through the apical membrane, which is critical for sodium reabsorption and fluid homeostasis. The presence of the α subunit is essential for channel function; mutations or dysregulation can cause inherited forms of hypertension or salt-wasting syndromes. The channel is non-voltage gated and regulated by hormones such as aldosterone. ENaC is a clinically validated target for potassium-sparing diuretics such as amiloride. Alterations in its regulation or function are implicated in cardiovascular, pulmonary, and renal pathologies.

Other names

Alpha-ENaCAmiloride-sensitive sodium channel subunit alphaENaC subunit alphaENaCAEpithelial Na(+) channel subunit alphaNonvoltage-gated sodium channel 1 subunit alphaSCNEASCNN1 (gene family root)Sodium channel epithelial 1 subunit alphaSCNN1A (gene symbol)

Direct inhibition of sodium influx: Amiloride directly blocks the ENaC at the extracellular side, reducing sodium reabsorption in the kidney, leading to natriuresis and diuresis. Hormonal regulation: Aldosterone increases channel transcription/expression, enhancing sodium reabsorption.