The Na+/H+ antiport of eukaryotic cells: relationship between the kinetic properties of the system and its physiological function.
The Na+/H+ antiport is present in the plasma membrane of virtually all vertebrate cells and it plays a central role in cell homeostasis. The pharmacological properties and the characteristics of the interaction of extracellular Na+, Li+, H+ and of intracellular H+ with the Na+/H+ antiport are reviewed herein. The kinetic properties of the system are shown to be essential for defining its four main physiological functions: transepithelial ion transport, control of the pHi, control of the intracellular Na+ concentration, and control of the cell volume. The activity of the Na+/H+ antiport can be modulated by a large number of effectors which are thought to act via protein kinases. At least three mechanisms of activation of the Na+/H+ exchanger are defined from the analysis of the kinetic properties of the system. Activation of the Na+/H+ antiport leads to very different consequences, depending upon the activity of other ion transporting systems in the membrane.
D000818:Animals; D002352:Carrier Proteins / Q000502:physiology*; D002462:Cell Membrane / Q000502:physiology; D002477:Cells / Q000201:enzymology*; D003327:Coronary Disease / Q000503:physiopathology; D003593:Cytoplasm / Q000502:physiology; D005057:Eukaryotic Cells / Q000201:enzymology* / Q000502:physiology; D005110:Extracellular Space / Q000502:physiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008094:Lithium / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers
D002352:Carrier Proteins; D017923:Sodium-Hydrogen Exchangers; D008094:Lithium