Fig. 3.

Mechanism of edema formation in ischemic and hemorrhagic stroke (see text for details). In ischemic stroke (above) AQP4 facilitates water uptake of perivascular astrocyte end-feet resulting in subsequent compression of the adjacent capillary lumen. As cellular damage evolves, the mechanism shifts into vasogenic edema and later hemorrhagic conversion. During hemorrhagic stroke, factors derived from the clot act on different components of the endothelial tight junction, leading the disruption of the BBB seal. AQP4 facilitates the reabsorption of edema fluid from the extracellular space