Major cation in ECF
Na, K ATPase catalyzes the hydrolysis of ATP to adenosine diphosphate (ADP) and uses the energy to extrude three Na+ from the cell to ECF and take two K+ into the cell for each molecule of ATP hydrolyzed.(REF: GANONG'S REVIEW OF MEDICAL PHYSIOLOGY 23rd EDITION page no.47.)
Na
K
PO4-2
Mg
General physiology