Coupling between Na+/H+ and Cl/HCO3 Exchange in pH and Volume Regulation

In recent years a variety of cell types have been shown to utilize Na⁺/H⁺ exchange to regulate cell volume or cytoplasmic pH. The present review will focus upon the biological and physical criteria which determine the extent to which net Na⁺/H⁺ exchange flux will alter the cellular volume and/or pH. We will speculate with regard to the control/sensing mechanisms responsible for the regulation of these parameters and their interplay. Initially, however, we will briefly review the criteria for identification of Na⁺/H⁺ exchange and the mechanisms that determine its activation and deactivation.