Simulating Cardiac Ventricular Action Potentials in Rat and Mouse

We have developed a computational model for the rat cardiac ventricular cell by using electrophysiology data. Our control model (Pandit et al., 2001). The model represents the bioelectric activity in the left ventricular cells in adult male rats. We have described the differences in the membrane properties within the left ventricle to simulate the action potential variations of the endocardial and epicardial cells. We also developed a right ventricular cell model from our control model (the left ventricular cell model) to study ionic mechanisms in diabetic rats (Pandit et al., 2003) Our right ventricular cell model was also the template for us to develop a mouse ventricular cell model by using experimental data. The simulation studies in our models of the rat and mouse ventricular cells conclude that (1) the action potential changes in the left and right ventricles of the normal, diabetic, aged or spontaneously hypertensive rats is mainly due to differences in the 4AP sensitive, Ca²⁺ independent transient outward K⁺ current (I_t) current, and (2) the presence of the 4AP sensitive, slowly inactivating, delayed rectifier K ⁺ current (I_Kslow) in mouse is one of the main factors contributing to the faster rate of repolarization seen in mouse compared to rats