Acidosis and Ca²⁺ current during an AP. Effect of acidosis on rabbit I_Ca,L during AP voltage clamps. The normal pipette filling solution (no BAPTA) was used in all experiments shown in this figure. The voltage templates used for control and acidosis are representative of APs recorded at a CL of 2 s during the three types of pH displacement. The same control AP waveform was used for each type of acidosis, and the same acidic AP waveform was used for both intracellular and combined acidosis. (A) Representative examples of AP clamps in control solution (black) and after 2 min of acidosis (red). Each type of acidosis reduced the initial peak value of I_Ca,L. The red arrow in the extracellular acidosis panel (left) indicates the initial peak I_Ca,L during acidosis. (B; a) Summary of results for initial peak amplitude of I_Ca,L (extracellular acidosis, n = 12; intracellular acidosis, n = 12; combined acidosis, n = 7). **, control versus acidosis; P < 0.01, paired. (b) Summary of results for net Ca²⁺ influx showing that extracellular acidosis decreased influx while the other types of acidosis increased influx. n values and statistics are the same as in B (a).