Effect of sodium inward current on extracellular potassium accumulation during myocardial ischemia: a simulation study

Myocardinal ischemia leads to extracellular potassium accumulation (Δ[K⁺]_o) and, as one of its consequences, to the development of reentrant arrhythmias, a major cause of sudden cardiac death. Subsequently, much attention has been paid to the study of mechanisms that could contribute to Δ[K]_o in ischemic myocytes. Nevertheless, the causes of this phenomenon are still poorly understood. Na-related mechanisms have been proposed as been in part responsible for the ischemic increase of K^- efflux. The authors of this paper incorporated a constant Na current of -1 μA/μF to the Luo-Rudy phase II action potential model. This modified version was used to simulate the electrical behavior of cardiomyocytes in the absence of coronary flow. The authors´ results show that the enhancement of Na influx leads to fast Δ[K]_a of 3.8 mmol/L