Extracellular potassium concentration fundamentally determines the resting membrane potential of cardiac cells, thereby directly dictating cardiac automaticity, heart rate, and electrical conduction velocity as established physiological principles.
The effect of extracellular potassium on cardiac resting membrane potential, excitability, heart rate, and conduction velocity is a foundational and universally taught principle of cardiovascular physiology and biophysics. Therefore, it falls under common knowledge, requiring no specific literature citation.