Sodium is the principal cation of extracellular fluid. It comprises more than 90% of total cations at its normal plasma concentration of approximately 140 mEq/liter. The sodium ion exerts a primary role in controlling total body water and its distribution.
Acetate (CH3COO-) is a hydrogen ion acceptor. It also serves as an alternate source of bicarbonate (HCO3-) by metabolic conversion in the liver. This conversion has been shown to proceed readily, even in the presence of severe liver disease.