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

The amiloride-sensitive epithelial Na+ channel regulates Na+ homeostasis in cells. Recently, we described that the delta-subunit is a candidate molecule for a pH sensor in the human brain. Here, an N-terminal spliced variant of the delta-subunit is cloned from human brain, and designated as the delta2-subunit, which is expressed with the original delta-subunit (delta1-subunit) at the same level in the human brain. Functional analyses revealed that the physiological and pharmacological properties (interaction with accessory betagamma-subunits, activation by acidic pH, amiloride sensitivity) of the delta2-subunit were similar to those of the delta1-subunit. In conclusion, the activities of both subunits may be involved in the mechanism underlying pH sensing in the human brain.