Figure 3.

A and C, cells were held at −40 mV. ATP (100 μm) activated outward currents and these responses were inhibited by apamin (1 μm, in A) or UCL1684 (1 μm, in C). Filled arrowheads denote ramp depolarizations applied before and during the period of ATP exposure (see ramp protocol in lower panels in B and D). B and D, expanded time scales of current responses to ramp protocols denoted by a and b in A and C, respectively. ATP (a) activated voltage-independent outward currents, and apamin (Bb) or UCL1684 (Db) inhibited the currents in responses to ATP. Dotted lines denote 0 pA. Short dash lines in pane A & C denote ATP applications.