Role of the ATP-sensitive potassium current in the development of reentry in a ring model of cardiac tissue. A computer simulation study

The aim of this work is to study the influence of activation of the ATP-sensitive potassium (K_ATP) current on vulnerability to reentry during cardiac hypoxia. A detailed mathematical model of this current was introduced into the Luo-Rudy model of the cardiac action potential (AP), and the electrical activity in a ID ring of cardiac tissue was simulated. To reproduce the natural dispersion of the sensitivity of the K_ATP current to [ATP]_i, the half-maximum inhibition constant of the channel was randomized following a Gaussian distribution. Hypoxia was simulated by appropriately reducing [ATP]_i and increasing [ADP]_i. The simulated hypoxic APs show a significant shortening compared to control APs, and spatial inhomogeneity of action potential duration (APD) is enhanced by inhomogeneous K_ATP current activation. Moreover, our results show that the hypoxic APD dispersion caused by opening of K^ATP channels could be enough to elicit reentrant activity.