 In the eccrine sweat glands, ENaC is predominantly located in the apical membrane facing the lumen of the sweat ducts.The major function of ENaC in these ducts is the re-uptake of Na⁺ ions that are excreted in sweat.In patients with ENaC mutations that cause systemic pseudohypoaldosteronism type I, the patients can lose a significant amount of Na⁺ ions, especially under hot climates.