Fig. 4.

Effect of a voltage clamp prestep on the response of I_to activation to extracellular acidosis (pH_o 6.5) in Epi myocytes. A: example experiment showing that, without a prestep to −40 mV, low pH_o has no effect on I_to activated by a voltage clamp step from −80 mV to +60 mV. B: example experiment (same cell as A) showing that low pH_o increased I_to when a 40-ms-duration prestep from −80 mV to −40 mV was included. C: summary of the results, expressed as % change in I_to relative to control with and without the prestep (n = 4). All experiments in this figure were performed in sodium- and Cd²⁺-free solution. Pacing CL = 5 s. **P < 0.01 paired, with vs. without prestep.