Fig. 1

Representative action potentials recorded in PV cardiomyocytes of rat (A), guinea pig (B), and rabbit (C). Spontaneous action potentials recorded in PV cardiomyocytes of guinea pig (D). The action potential indicated by the arrow is shown in an expanded time scale in the right panel. Typical tracings recorded from the PV cardiomyocytes of rabbit are an elicited action potential (Ea) and subsequent spontaneous electrical activity (Eb) after the train stimulation at a pacing cycle length of 2 s. The action potential indicated by the arrow is shown in an expanded time scale at the right panel. Dashed lines indicate 0 mV