What is the Origin of Epithelial Sodium Channels?

The term combines "epithelial," referring to the tissue layer lining organs and cavities, with "sodium channels," denoting their function as pores for sodium ion transport. Their clinical significance is deeply rooted in renal physiology and endocrinology, particularly concerning the Renin-Angiotensin-Aldosterone System (RAAS). Aldosterone, a mineralocorticoid, is the key hormonal regulator of ENaC activity.

What is the Mechanism of Epithelial Sodium Channels?

ENaC activity is primarily controlled by aldosterone, which binds to intracellular mineralocorticoid receptors in the principal cells of the kidney's collecting duct. This binding initiates gene transcription that increases the synthesis and insertion of ENaC proteins into the apical membrane, alongside increasing the activity of existing channels. The resulting increase in sodium reabsorption drives water retention, which helps to maintain plasma volume and systemic blood pressure homeostasis.

Epithelial Sodium Channels ∞ Area

Epithelial Sodium Channels

Meaning

Epithelial Sodium Channels, often abbreviated as ENaC, are selective ion channels located on the apical membrane of epithelial cells in organs like the kidney, colon, lung, and sweat glands. Their primary function is to mediate the passive reabsorption of sodium ions from the lumen into the cell, which is a key determinant of fluid and electrolyte balance and blood pressure regulation. These channels are direct targets of mineralocorticoid hormones.