Markovian model for wild-type and mutant (Y1795C and Y1795H) human cardiac Na+ channel

Long QT syndrome (LQTS) and Brugada syndrome (BrS) are inherited syndromes predisposing to ventricular arrhythmias and sudden death. Emerging evidences related LQTS and BrS to dysfunctions of cardiac ion channels. Recently, two novel missense mutations in gene encoding for the cardiac Na channel have been identified (Y1795C for LQTS and Y1795H for BrS). Both mutations alter inactivation, intermediate inactivation, onset of inactivation of Na current and cause a sustained Na current. In this study we present a Markovian model of wild type and mutant Na channels. Model includes three closed states, an open state, and five inactivated states. Transition rates between these states were identified on the basis of electrophysiological experiments. The model is able to reproduce the current alterations observed in mutant channels just by alter the transition rates with respect to wild type assignment.