Fig. 4.

Effect of small-conductance Ca²⁺-activated K⁺ (SK) channel blockers on the outward currents activated by UTP in PDGFRα⁺ cells. A and C: cells were held at −40 mV. UTP (10 μM) activated outward currents, and these responses were inhibited by apamin (0.3 μM; A) or UCL1684 (1 μM; C). B and D: expanded timescaless at points denoted by a and b in A and C showing the outward currents activated by UTP (B,a and D,a); these currents were blocked by apamin (B,b) or UCL1684 (D,b). Horizontal dotted lines in all A–D denote 0 pA. Arrowheads denote the application of ramp potentials (see protocols shown in bottom traces in B and D).