Ionic Mechanism of Propagation in Human Purkinje fiber Cells: Role of Calcium Ions and Calcium Channels - a Simulation Study

Abstract

An important ailment that requires treatment by the physician is cardiac failure (“Heart Failure (HF)”), which usually decreases the contractility of the myocardium. The Purkinje Fibre Cells (PFC) augurs to be an important biological network of the human cardiac ventricular conduction system. It assuages to be tertiary pacemaker of the heart which synchronizes the ventricular conduction. This work analyzes the effects of calcium ionic mechanism of propagation using the Zhang model. The strength of contraction of cardiac muscle depends to a great extent on the concentration of calcium ions in the extracellular fluids. The calcium ions also play vital role in excitation, contraction coupling and cardiac muscle relaxation. The model attempts to increase the influx of calcium concentration (0.000156 mM) from the normal Ca2+ (0.000102 mM) value and also to increase the extracellular calcium concentration ([Ca2+]o) (3 mM). The result show that the internal rise of calcium concentration increased excitability of PFC and maintain plateau potential throughout propagation. Similarly, the high calcium level in extracellular and low calcium level in intracellular decreased excitability of PFC and affect propagation diastole relaxation period. The Calcium channels appear to play a major role in sustaining conduction and propagation when low calcium level in intracellular fluids. The abnormal calcium concentration may affect the PFC excitability and Conduction velocity, which in turn can lead to cardiac ventricular arrhythmias.