ATP-evoked biphasic currents were not observed in SC microglia of P2X7R−/− mouse embryos. A, PCR results for wild-type (+/+) mice, heterozygote mice (+/−), and P2X7R KO mice (−/−). B, Voltage-current relationship of microglia recorded in the SC of E13.5 P2X7R−/− mouse embryos. A voltage ramp protocol (−100 mV +100 mV; 2 s) was used to investigate voltage-activated currents. C1, Application of 3 mm ATP on microglia recorded in the SC of P2X7R −/− mouse E13.5 embryo failed to evoked large biphasic inward currents. C2, Examples of currents evoked by 3 mm ATP on microglia of a P2X7R +/− mouse E13.5 embryo. C3, Histogram showing differences in current density of 3 mm ATP-evoked responses in SC microglia of P2X7R −/− (0.93 ± 0.43 pA/pF; N = 5) and P2X7R +/− (16.5 ± 2.12 pA/pF; N = 7) mouse embryos. (Vh = −60 mV). Input capacitance of recorded microglia in P2X7R−/− embryos (11.9 ± 1.4 pF; N = 5) and in P2X7R +/− embryos (10.3 ± 1 pF; N = 7) were not significantly different (p > 0.1). Error bars indicate SEM.