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. Author manuscript; available in PMC: 2014 Apr 1.
Published in final edited form as: Nat Rev Neurosci. 2013 Mar 13;14(4):265–277. doi: 10.1038/nrn3468

Figure 4. Aquaporin 4 involvement in astrocyte migration and neuroexcitation.

Figure 4

a | Aquaporin 4 (AQP4) has a proposed role in astrocyte migration. Water is driven into the cytoplasm primarily through AQP4 in the lamellipodium by an osmotic gradient created by actin depolymerization and active solute influx (left), facilitating lamellipodial extension in the direction of cell migration (right). b | AQP4 is also proposed to have a role in neuroexcitation outside the synaptic cleft (left panel). Neuroexcitation involves isosmolar K+ release by neurons and uptake of K+ and water by astrocytes (centre panel). AQP4 facilitates water entry into astrocytes, resulting in contraction of the extracellular space (ECS) volume and increased ECS K+ concentration ([K+]; right panel), which further drives astrocyte K+ uptake.