Epithelial Na+ channel δ subunit mediates acid-induced ATP release in the human skin

The amiloride-sensitive epithelial Na+ channel (ENaC) regulates Na+ homeostasis in cells and across epithelia. Although we described that ENaCδ is a candidate molecule for a pH sensor in the human brain, the physiological and pathological roles of ENaCδ in non-neuronal tissues are still unknown. Here we show a novel physiological function of ENaCδ in peripheral tissues in humans. Expression analyses at the level of mRNA clearly revealed that ENaCδ was abundantly expressed in human epidermis and keratinocytes. In addition, ENaCδ protein was detected in there. In cultured keratinocytes, acidic stress (pH 5.0) evoked ATP release, which was significantly reduced in the presence of 100 μM amiloride or 10 μM benzamil. In conclusion, ENaCδ may be involved in the mechanism underlying pH sensing followed by the regulation of cell viability in the human skin.