Walch et al. (2020) suggested that the role of AQP4 in the volumetric response of astrocytes induced by hyperkalemia is in the water efflux from the cells. It limits the astrocytic swelling and thus its deletion leads to an increase in the astrocyte volume (Walch et al., 2020) the same as we detected in HRA from Aqp4–/– mice. On the contrary, we detected a decreased volume of LRA from the Aqp4–/– mice, indicating involvement of other factors such as location/contacts with other cell types. The gene discussed is AQP4; the disease is Hyperkalemia.