However, AQP4 channels seem to be involved in the removal of water from astrocyte and in their volume recovery, which also likely explains the worsening of cerebral edema in Aqp4–/– mice in the experimental models of subarachnoid hemorrhage or permanent middle cerebral artery occlusion (MCAO) (Manley et al., 2004; Tait et al., 2010). This evidence concerns the gene AQP4 and subarachnoid hemorrhage.