Figure 7. Maximal diastolic potential and the control of DF_max gradients.

A, MDP was clamped at varying predetermined values. The APD and activation ratio were allowed to change. The MDP ranged from the unclamped values (5 × G_Kr, −72 mV; 1 × G_Kr, −70 mV) to −62 mV. B, spatial DF profiles correspond to MDP as indicated. The DF in the 5 × G_Kr region is insensitive to MDPs more negative than −67 mV, remaining at 14.7 Hz. The rotor frequency decreases when clamped MDP is less negative than −66 mV and wavebreak ceases. C, rotor DF_max (black) and n:m change (grey) change as functions of MDP in the infected region. For MDP of −68 mV and more negative, DF and n:m remain constant.