Sodium fluxes and astroglial function

Astrocytes exhibit their excitability based on variations in cytosolic Ca²⁺ levels, which leads to variety of signalling events. Only recently, however, intracellular fluctuations of more abundant cation Na ⁺ are brought in the limelight of glial signalling. Indeed, astrocytes possess several plasmalemmal molecular entities that allow rapid transport of Na⁺ across the plasma membrane: (1) ionotropic receptors, (2) canonical transient receptor potential cation channels, (3) neurotransmitter transporters and (4) sodium-calcium exchanger. Concerted action of these molecules in controlling cytosolic Na⁺ may complement Ca²⁺ signalling to provide basis for complex bidirectional astrocyte-neurone communication at the tripartite synapse.