Sex and age related differences in drug induced QT prolongation by dofetilide under reduced repolarization reserve in simulated ventricular cells

The aim of this study was to investigate sex and age related differences in drug induced QT prolongation by dofetilide under reduced repolarization reserve in simulated ventricular cells. Left ventricular endocardial action potentials were simulated using a modified Luo Rudy model. Sex, age and regional differences in currents I_CaL, IK_r, IK_s, and I_to were incorporated into the model by modifying the equations representing them. A model of dofetilide, a class III antiarrhythmic drug, was developed and included into a ventricular cell models. The reduced repolarization reserve was reproduced decreasing the IKs current. Our results shown that the adult female cells had longer action potentials, a steeper APD-BCL relationship and a higher susceptibility to EADs than adult male cells, under control, drug induced and reduced repolarization reserve conditions. On the other hand, young female and young male cells had similar action potentials under control conditions. However, young male cells had longer action potentials and higher susceptibility to EADs than young female cells under drug induced and reduced repolarization reserve conditions. Sex and age dependent differences in I_CaL, IKr, IKs, and Ito may explain the age and sex disparities in prolongation of APD by the action of dofetilide.