HL-1 Cardiac Muscle Cell Line is an immortalized mouse cardiomyocyte cell line able to continuously divide and spontaneously contract while maintaining a differentiated cardiac phenotype. HL-1 can be serially passaged without losing its differentiated cardiac myocyte phenotype, including morphological, biochemical, and electrophysiological properties. HL-1 is used in a variety of model systems to address questions of cardiac biology at the cellular & molecular levels.