A novel spliced variant of the epithelial Na+ channel δ-subunit in the human brain

The amiloride-sensitive epithelial Na+ channel regulates Na+ homeostasis in cells. Recently, we described that the δ-subunit is a candidate molecule for a pH sensor in the human brain. Here, an N-terminal spliced variant of the δ-subunit is cloned from human brain, and designated as the δ2-subunit, which is expressed with the original δ-subunit (δ1-subunit) at the same level in the human brain. Functional analyses revealed that the physiological and pharmacological properties (interaction with accessory βγ-subunits, activation by acidic pH, amiloride sensitivity) of the δ2-subunit were similar to those of the δ1-subunit. In conclusion, the activities of both subunits may be involved in the mechanism underlying pH sensing in the human brain.