A, time course of extracellular ATP-induced whole-cell currents in standard extracellular solutions in intracellular GTPγS dialysed cell of wild-type mouse. ATP (100 μm), DIDS (100 μm) and glibenclamide (100 μm) were applied during the times indicated by each bar. B, mean I–V relationships of DIDS- (e–f) and glibenclamide-sensitive currents (e–g), which were obtained from whole-cell recordings induced using the same voltage clamp pulse protocol shown in Fig. 1B, at time points e, f and g in A. C, the left side shows the mean (n = 4) difference current density at +100 mV in DIDS, DIDS and ATP, and ATP following the removal of DIDS in control (absence of GTPγS) cells. The right side shows the mean (n = 4) difference current densities at +100 mV in suramin, suramin and ATP, and ATP following removal of suramin. * and ** signify significantly smaller than ATP alone with P < 0.05 and 0.01, respectively.