BzATP- induced currents in oocytes expressing the human P2X7R. The membrane potential was clamped at −60 mV, and brief 10-mV pulses were applied at a rate of 0.1 Hz for assessment of changes in membrane conductance. The currents and conductance changes induced by 100 µM BzATP were either sustained (A) or diminished (B) over time, despite the presence of the stimulant depending on the batch of oocytes. BzATP-induced currents in oocytes were inhibited by BBG but not by BB FCF (C–E). Experimental conditions were the same as in A, except the inhibitors BB FCF and BBG were included. (C) In the presence of 100 µM BB FCF, membrane currents of significant amplitude were induced by BzATP, which were attenuated by 10 µM BBG. (D) When applied in the presence of BzATP, the induced currents were minimally affected by 100 µM BB FCF. (E) Quantitative analysis of membrane currents induced by BzATP in the presence of 100 µM BB FCF or of various concentrations of BBG. Means ± SD are plotted, and n is indicated.