Reaching out beyond the synapse: glial intercellular waves coordinate metabolism.

Neuronal activity can stimulate an increase in astrocyte intracellular calcium concentration, which is propagated through neighboring astrocytes as a "calcium wave"; these calcium waves are accompanied by the release of glutamate. Sodium-dependent glutamate uptake leads to a secondary astrocytic sodium wave, accompanied by a wave of increased glucose uptake and metabolism. This metabolic wave may enable astrocytes to provide lactate as an energy source to neighboring active neurons and perhaps to distant neurons as well. Thus, one function of long-range intercellular calcium signaling in astrocytes may be to spatially coordinate their function in supporting neuronal metabolism.