part of membrane depolarization ventricular cardiac muscle cell action potential membrane depolarization during cardiac muscle cell action potential membrane depolarization during ventricular cardiac muscle cell action potential The process in which ventricular cardiac muscle cell membrane potential changes in the depolarizing direction from the negative resting potential towards the positive membrane potential that will be the peak of the action potential. GO:0098913 biological_process ventricular depolarization electrocardiogram QRS complex