AQP4 and Hypertension: Several mechanisms have been reported to mediate the hypertension-caused BBB disruption, including enhanced transendothelial cell transport (Tagami et al., 1983), structure change in TJ and altered distribution of glucose transporter-1 (Lippoldt et al., 2000), increased expression of AQP4 in the end feet of astrocytes (Ishida et al., 2006), and the like.