Under physiological conditions, the Na+/H+ exchanger mediates the exchange of one extracellular Na+ ion for one intracellular proton, thereby keeping the overall charge neutral. The extracellular binding site of Na+ is not selective as it can also bind Li+ and H+ . K+ ions inhibit NHE-1 but have no effect on NHE-27. The activation of NHE-1 and NHE-2 is sensitive to intracellular acidic pH. Under physiological conditions, both exchangers are not active and upon a drop of intracellular pH, they are rapidly activated.NHE-1 expression is ubiquitous and may serve as a housekeeping gene
