Extracellular ATP increases the open time of GABA single-channel activity in outside-out mode in hippocampal neurons. Outside-out GABAAR gated single channel activities were recorded by bath application of GABA (0.5 μM) to the excised patches through bath applications (A, Left) in absence (GABA; 0.5 μM) or presence of ATP (+ATP 1 mM) or ATP + bicuculline (+bicuculline 10 μM) in the bath or after drug washout (Washout). Suramin (100 μM) and BBG (1 μM) were added in the bath throughout the recording to block P2 receptors. A, Representative GABA current traces were obtained 5 min before (GABA 0.5 μM) and after drug applications or washout as indicated above traces. In this patch, P
increased from 0.15 in the control (GABA) to 0.28 after addition of ATP. B, Current-voltage relationship of GABA single channel activity in the absence (Control) and presence of ATP (1 mM) at various holding membrane potentials. C and D, Bar graphs summarizing the mean P
(L eft) and open times (Right) in the absence (GABA) and presence of ATP (GABA + ATP) from seven cells. ** P < 0.01.