AQP4 and Alzheimer disease: However, high Aβ burden in AD results in loss of Kir4.1 potassium channels, as well as aquaporin 4 (AQP4) channels which are also hypothesized to be critical for glymphatic function (Wilcock et al., 2009; Nedergaard, 2013; Kress et al., 2014; Zeppenfeld et al., 2017).