Simulation of effects of inward-rectifier K+ current on the automaticity of human ventricular tissue

Inward-rectifier K+ current (IK1) is a major current in ventricular myocytes, which contributes both to the fourth phase of repolarization and setting the resting membrane potential. The down-regulation of IK1 could induce automaticity in human ventricular myocytes. An idealized 2D human ventricular tissue was designed in this paper, which was 100 cells in length and 400 cells in width. The effects of IK1 were both investigated on single ventricular cell and the tissue. The experimental results demonstrated that the lower the IK1, the higher the automatic rhythm. The autorhythmicity increased with the decreasing of IK1. The tissue was controlled by the automatic rhythm when IK1 was less enough; in contrast, it was controlled by the sinus rhythm when IK1 was larger than a critical value.