Fig. 4.
Effect of the P2 receptor antagonist suramin on the train of APs evoked by ATP. Representative voltage traces from a single AH neuron; the dotted lines indicate RMP. Calibration in C applies to all traces. The total number of APs is shown to the right of eachtrace. A, ATP (2 mm, 100 msec; applied at the filled triangle) elicited a train of 12 APs at an average instantaneous frequency (fINT) of 30 Hz for a duration of 0.8 sec. B, The response was not reduced by suramin (100 μm) (17 APs; ƒINT of 16 Hz; duration of 2.1 sec). C, Thirty minutes after washout, the response is shorter and of a higher frequency than in suramin (13 APs;fINT of 30 Hz; duration of 1.0 sec) (RMP, control, −69 mV; suramin, −70 mV; recovery, −65 mV).