Figure 2. Simultaneously recorded action potentials and [Ca²⁺]_i signals from a spontaneously firing toad pacemaker cell.

A, simultaneously recorded action potentials (upper panel) and calcium transients (lower panel). Action potentials were recorded using the nystatin perforated-patch technique and have been corrected for the calculated liquid junction potentials (−5 mV). B, superimposed action potential and [Ca²⁺]_i from a different cell from A. The action potential data has been smoothed with 10 Hz low-pass filter to match the filtering of the [Ca²⁺]_i signal.