part of part of in taxon membrane depolarization membrane depolarization during cardiac muscle cell action potential SA node cell action potential membrane depolarization during SA node cell action potential membrane depolarization involved in regulation of SAN cardiac muscle cell action potential membrane depolarization involved in regulation of sinus node cardiac muscle cell action potential 2011-11-16T10:52:57Z membrane depolarization involved in regulation of SA node cardiac muscle cell action potential GO:0086046 biological_process The process in which SA node 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. membrane depolarization involved in regulation of sinoatrial node cardiac muscle cell action potential Bacteria Schizosaccharomyces