CI⁻

The main anion (negatively charged ion) of the extracellular fluid.

Cloride (Cl⁻) plays an important role in several physiological processes such as the action potential of skeletal muscle cells, CO₂ transport in blood (via Cl⁻/bicarbonate exchange across the plasma membrane of red blood cells), and many other processes.

The extracellular concentration of Cl⁻ is about 110 mM. The intracellular concentration of Cl⁻ is about 10 mM.