Fig. 5.

Effect of a voltage clamp prestep and Cd²⁺ (200 μM) on the response of I_to activation to intracellular acidosis (80.0 mM acetate) in Epi myocytes. A: example experiment showing that, in the presence of the 40-ms prestep and normal external sodium, low pH_i reduced I_to both with (a) and without (b) the presence of Cd²⁺ and example signals from a cell showing that, in sodium- and Cd²⁺-free solution, low pH_i reduced I_to both with (c) and without (d) the 40-ms prestep. B: summary of results, expressed as % change in I_to relative to control. There were no significant differences among these groups (ANOVA); n = 9 with prestep, normal sodium, and Cd²⁺; n = 4 with prestep, normal sodium, no Cd²⁺; n = 4 with prestep, no sodium, no Cd²⁺; n = 4 with no prestep, no sodium, no Cd²⁺. Pacing CL = 5 s.