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Quantitative modelling of effect of transverse - axial tubular system on electrical activity of cardiac cells: Development of model II
Pásek, Michal ; Christé, G. ; Šimurda, J.
In this work, we present a new version of cardiac ventricular cell model incorporating the transverse - axial tubular system. The improvements include reformulated description of L-type Ca2+ channel, of Ca2+ induced Ca2+ release from sarcoplasmic reticulum, of intracellular Ca2+ buffering and incorporation of potassium currents Ito, IK(Na) and IK(ATP). In comparison with the previous model (Pásek et al., 2002), the steady state simulations revealed more profound changes of tubular ionic concentration (12.8 % for Ca2+ and 4.7 % for K+ at 1 Hz). The refined model will be used for more exact quantitative exploration of the effect of transverse - axial tubular system on cellular electrical activity and excitation - contraction coupling.
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Quantitative modelling of effect of transverse-axial tubular system on electrical activity of cardiac cells under low [K+]e
Pásek, Michal ; Christé, G. ; Šimurda, J.
In this work, we explored quantitatively the effect of ion concentration changes in the restricted space of transverse-axial tubular system (TAT-system) on ventricular cell arrhythmogenesis under the conditions of low extracellular potassium concentration ([K+]e). The simulations were performed on a model that integrates the quantitative description of electrical activity of surface and tubular membrane with the quantitative description of dynamic changes of intracellular ion concentrations. The results predict that the TAT-system plays a significant protecting role in cellular arrhythmogenesis that arises from the enhancement of potassium concentration gradient between tubular and extracellular spaces at low level of [K+]e.
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Quantitative modelling of effect of transverse-axial tubular system on electrical activity of cardiac cells: development of model
Pásek, Michal ; Christé, G. ; Šimurda, J.
The transverse-axial tubular system (TAT-system) of cardiac muscle is a structure that allows rapid propagation of excitation into the cell interior. As suggested in many recent experimental works, it could have a significant effect on cardiac cell function induced by the accumulation or the depletion of ions in restricted tubular space. In our previous work [27], the basic properties of TAT-system were formulated and preliminary simulations characterizing its effect on cellular electrical activity realised. In this article, we describe the design of a more complex model of ventricular myocyte based mostly on data from guinea pig. The model integrates the description of electrical activity of surface and tubular membranes with the detailed description of mechanisms controlling the intracellular and tubular ion concentrations.
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