Generation of early afterdepolarization in mouse ventricular fibers at long cycle length

Early afterdepolarization (EAD) was studied in ventricular fibers of mouse heart. EAD could be occasionally induced under long cycle length of superfusion with Tyrode's solution (containing 3.0 or 5.0 mM KCl) at long cycle length. Three types of EAD were found: a second plateau with a prominence, a single triggered burst and a train of triggered bursts. Take-off potential of the first triggered burst or of the prominence varied from -40 to -60 mV. The triggered bursts in the third type often stopped at -35 to -45 mV level forming a very long second plateau before it completely repolarized. Changing abruptly from a long cycle length to a short one lead to a transient EAD induction. It is suggested that EAD in ventricular fiber in mouse heart shared the characteristics of that in atrial fibers, although it was very difficult to induce and was not very reproducible.