Simulation of triggered activity and abnormal automaticity in ventricular myocytes

The goal of this work is to theoretically study the effect of cellular coupling on generation of triggered activity and abnormal automaticity in cardiac ventricular myocytes. We have used a computer model of the ventricular action potential in a system of two cells coupled by a resistance R. With [Ca]/sub i/=0.5 /spl mu/M, the spontaneous activity varies from two action potentials followed by three DADs at R=10 M/spl Omega/ to eight action potentials for complete uncoupling. Under early afterdepolarization (EAD) conditions, EADs appear on the AP plateau for complete uncoupling thus provoking lengthening. When the value of R is decreased, the APD becomes substantially shortened. However, at a value of R for which the action potential is propagated a prolongation of APD is again produced. Therefore, the coupling resistance may affect triggered activity and abnormal automaticity formation.