Sodium-Potassium Adenosine Triphosphatase is an Enzyme Present in All Cells that Catalyzes the Conversion of Adenosine Triphosphate (ATP) to Adenosine Diphosphate (ADP)

(From Ganong WF. Review of Medical Physiology. 21st ed. New York, NY: Lange Medical Books/McGraw-Hill; 2003.)

The resulting energy is used by the active transport carrier system (sodium-potassium pump) that is responsible for the outward movement of three sodium ions across the cell membrane for every two potassium ions that pass inward.