Computer simulation of action potential duration inhomogeneities in cardiac hypoxia, role of the ATP-sensitive potassium current

A mathematical model of the ventricular action potential has been used to study the contribution of the ATP-sensitive K⁺ current (I_K(ATP)) to the spatial differences in action potential duration (APD) observed in cardiac hypoxia. A model of I_K(ATP) has been formulated and introduced into the Luo-Rudy model of the ventricular action potential. Hypoxia was simulated in a one-dimensional linear model of the cardiac tissue. The sensitivity of K(ATP) channels to intracellular nucleotide levels was randomized, simulating the natural dispersion of this parameter. The results show that I_K(ATP) activation significantly reduces APD and Increases its spatial dispersion. The mean value of APD obtained under normoxic conditions was 154.5 ms, decreasing to 85.5 ms when hypoxia was simulated. The spatial APD coefficient of variance increases from 0.429b to 2.20 in said situations. Thus, I_K(ATP) activation can cause spatial dispersion of APD in cardiac hypoxia