Seyed Hojat Sabzpoushan; Azadeh Ghajarjazy
Volume 9, Issue 3 , December 2015, , Pages 267-282
Abstract
Time constant is a physical concept that one may deduce the speed of response and reaction of a system from it. Experimental findings confirm the dependency of the speed of opening-closing of ionic channels to the membrane voltage. In this paper a model for time constant of membrane voltage in neurons ...
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Time constant is a physical concept that one may deduce the speed of response and reaction of a system from it. Experimental findings confirm the dependency of the speed of opening-closing of ionic channels to the membrane voltage. In this paper a model for time constant of membrane voltage in neurons has been presented. At first, the presented model has been established as a theorem and then the theorem has been proved. According to the presented theorem, one can simulate different morphology and time course of action potential (AP) in neurons by adjusting the model parameters. The validation of the presented theorem (model) has been shown by simulation examples of some kinds of neurons and cells APs. Regarding the generality of the presented theorem, our model not only can be applied in biomedical systems but also it may be used in any physical systems.
Biological Computer Modeling / Biological Computer Simulation
Seyed Hojat Sabzpoushan; Niloofar Shahidi; Azadeh Ghajarjazy
Volume 9, Issue 4 , February 2015, , Pages 351-360
Abstract
Abnormal oscillations of ventricular cell action potential can lead to cardiac arrhythmias. Early afterdepolarizations (EADs) is one kind of these oscillations that have been widely studied in the field of cardiac arrhythmias diagnosis and therapies. Nowadays although ventricular cell models have been ...
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Abnormal oscillations of ventricular cell action potential can lead to cardiac arrhythmias. Early afterdepolarizations (EADs) is one kind of these oscillations that have been widely studied in the field of cardiac arrhythmias diagnosis and therapies. Nowadays although ventricular cell models have been developed, yet dynamical mechanisms of EADs remain unknown that need more researches. In this paper, using phase plane analysis of a minimal model of ventricular cell, we show that EADs are occurred as a result of Hopf and homoclinic bifurcations in ventricular cell. We also show that during period pacing, chaos happens at the transition from no EAD to EADs. This result provides a distinct explanation for the EAD behavior of the cardiac cells and also explains EADs dynamics in accordance with experiment results. While this research was performed for ventricular cells, but the achieved results can be extend to other excitable systems and used in the prediction of oscillation due to the changes of system parameters.
