Distribution of P2X4-pHluorin123 receptors in cultured hippocampal neurons and C8-B4 microglia. (A and B) Representative images of P2X4-pHluorin123 receptors expressed in cultured hippocampal neurons and C8-B4 microglia under the conditions indicated (pH 7.4, pH 5.4, and 50 mM NH₄Cl). (C) Representative traces for ATP-evoked currents recorded from neurons and C8-B4 microglia (average data are reported in the Results). (D) Distribution of P2X4-pHluorin123 receptors in cellular compartments of neurons and C8-B4 microglia (somata and processes are separated). (E) Graphs show average data for C8-B4 microglia ROIs in somata and processes. (F) Representative traces for ATP-evoked currents for WT P2X4-pHluorin123 and for P2X4-pHluorin123 carrying quadruple mutations that block lysosomal targeting and endocytosis. (G) Summary data showing that proportions of P2X4-pHluorin123 receptors in cellular compartments of C8-B4 microglial somata and process ROIs are altered in quadruple mutant channels; the cell surface fraction increases significantly. Error bars represent mean ± SEM.