SLC4A4 and ischemic stroke: Pathological pH decline is often observed after ischemic stroke, partially owing to hypoxia, which then triggers a sharp response by ion transporters across multiple cell types.18 Recent studies showed that Slc4a4 is activated and releases HCO3− to neutralize rapid acidification from synaptic transmission.25 It is reported that loss of astrocytic Na+/H+ exchanger isoform 1 (NHE1) reduced astrogliosis and ameliorated BBB damage.62 The functional difference between Slc4a4 and NHE1 should be noted.