Strain-dependent stretch-activated ion channel in Hodgkin- Huxley-form models of ventricular cardiomyocyte action potential

The electrophysiology of cardiac myocytes is tightly coupled to mechanics. One aspect of this is apparent in the effects of mechanical strain on cardiac action potential dynamics. These can be considered through adjustments to classic electrophysiological models. The standard FitzHugh Nagumo model is a reduced two-variable model from Hodgkin-Huxley that can reproduce basic mechanisms of action potential dynamics. A modified formulation that adapts the model to ventricular cardiomyocytes is considered. The Luo-Rudy model is also a Hodgkin-Huxley-derived model for action potentials driven by ionic currents in cardiac myocytes. The Healy-McCulloch model predicts a decrease in time for 20% action potential repolarization and variable time for 90% action potential duration as seen in rabbit ardiomyocytes based on tiered conductance values. Recently, Lunze and Leonhardt provide a mathematical relation for stretch-activated conductance and strain in smooth muscle. This paper determines whether the Lunze-Leonhardt model for stretch-activation of ionic currents can be applied to a cardiomyocyte model. Using Matlab and Continuity, we will develop a modified model derived from the FitzHugh Nagumo and Luo-rudy models by incorporating a strain-dependent ion channel. We will simulate several coupled cardiomyocytes in Matlab with this modified model to reproduce the results of the Healy-McCulloch model. The modified FitzHugh Nagumo model is also implemented in a finite element simulation study the effects of a strain field on action potential propagation.