When the ischemic zone involves the entire thickness of the ventricular wall, i.e. is transmural, the injury current generated during the resting phase (phase 4) of the action potential will flow from the more positive region (the ischemic zone - the red action potential) where the resting membrane potential is -65 mv , to the more negative region (the normal zone - the blue action potential) where, as depicted in this figure, the resting membrane potential is -85 mv. Thus, during this phase of the action potential the injury current will flow away from the ischemic zone to the non-ischemic zone. This will cause depression of the TQ segment in electrograms recorded by electrodes placed directly over the ischemic region.