Simulation study of the contribution of the ATP-dependent potassium current to extracellular potassium accumulation during myocardial ischemia

In this paper, computer simulations have been carried out to study the contribution of the ATP-dependent K⁺ current (I_K(ATP)) to extracellular K⁺ accumulation during acute myocardial ischemia. The I_K(ATP) model described by Ferrero et al. [1996] was introduced into the Luo-Rudy phase II action potential model [1994]. A Na-H exchanger was also formulated and used to balance ion concentrations during normoxia. I_K(ATP) current was activated in a linear manner for ten minutes of simulated ischemia from 0% to different maximum values. The effect of heart rate was tested considering different basic cycle lengths (BCL) of stimulation. Our results show that the contribution of I_K(ATP) to the increase of extracellular K⁺ concentration ([K⁺]) during acute myocardial ischemia represents less than 25% of the experimentally observed K⁺ accumulation. This results supports the hypothesis that other mechanisms contribute significantly to the ischemic increase of extracellular K⁺ concentration