Simulation study of action potentials during acute myocardial ischemia

In this work, computer simulation has been used to study the main features of action potentials (APs) elicited in myocardial tissue when regional acute ischemia is present. For this purpose, the Luo-Rudy (phase II) model of the cardiac AP has been used with the formulation of the ATP-sensitive K⁺ current by Ferrero et al. (1996) being adopted. Simulations of APs were carried out in a linear strand of 300 cardiac cells, which comprised three zones that represented the normal zone, borderzone and ischemic central zone which appear during regional ischemia. The authors´ results show that: (a) basic stimuli elicit APs which correspond to depressed fast responses, with the upstroke being supported mainly by Na⁺ current; and (b) a premature stimulus gives rise to APs which are Ca²⁺ dependent (slow responses) within the ischemic central zone