Figure 1.

Agonist-induced Ca²⁺ signaling in astrocytes might work through lowering extracellular K⁺ to affect synaptic activities.

Agonist-induced astrocytic Gq-linked receptors trigger release of intracellular IP3 and mobilize Ca²⁺ endoplasmic reticulum (ER) Ca²⁺. Intracellular Ca²⁺ is transported outwards across the membrane by the Na⁺,Ca²⁺ exchanger (NCX) at the expense of Na⁺ influx. In turn, elevation of cytosolic Na⁺ activates the Na⁺,K⁺-ATPase, leading to a decrease in extracellular K⁺. The effect of Ca²⁺ wave on glutamate clearance is unclear. The figure is modified from Wang et al. (2013). CRAC: Ca²⁺ release activated Ca²⁺.