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The influence of anisotropy on excitation wave propagation in neonatal rat cardiomyocytes monolayer.

Name
Aygul
Surname
Nizamieva
Scientific organization
Laboratory of the Biophysics of excitable systems, Moscow Institute of Physics and Technology
Academic degree
No
Position
student
Scientific discipline
Life Sciences & Medicine
Topic
The influence of anisotropy on excitation wave propagation in neonatal rat cardiomyocytes monolayer.
Abstract
This work is devoted to various models of the cardiac arrhythmias and the modeling of the spiral wave formation, in particular. To create controlled anisotropy in a cultured cell layer for cardiac arrhythmias models we used a photosensitive agent AzoTAB. In this paper, two main models have been created: the model of unidirectional block and the model with a gradient of excitability. Also simulations were calculated theoretically on the Aliev-Panfilov model.
Keywords
Azotab, photocontrol, arrythmia, optical mapping, heart disease, ablation
Summary

 

The influence of anisotropy on excitation wave propagation in neonatal rat cardiomyocytes monolayer.

Nizamieva A., Kalita I., Tsvelaya V., Kudryashova N., Agladze K.

Moscow Institute of Physics and Technology

 

Cardiac arrhythmias are among the most common causes of death in the world, therefore studying mechanisms of their initiation is one of the priorities of modern science. This work is devoted to various models of the cardiac arrhythmias and the modeling of the spiral wave formation, in particular. To create controlled anisotropy in the cultured cell layer for cardiac arrhythmias models we used a photosensitive agent of azobenzene-based compounds called AzoTAB ((2- {4- [(E) -2- (4-ethoxyphenyl) diazo-1-yl] phenoxy} ethyl) trimethylammonium bromide). In the dark, thermally relaxed state or in a state under blue light (λ> 440 nm) trans-AzoTAB reversibly reduces spontaneous activity and the rate of propagation of excitation waves until absolute blockade. Excitation waves may be renewed by near-UV irradiation (λ ≈ 365 nm), which converts AzoTAB to the cis-form. In this paper, two main models have been created: the model of unidirectional block and the model with a gradient of excitability.

 

The model of a unidirectional block relies on a creation of inhomogeneous excitability in the tissue. In areas irradiated by UV-light the activation threshold of excitation is lower compared to the non-irradiated or weaker irradiated areas, so in a presence of abrupt UV gradient (at certain concentrations of AzoTab) excitation wave passes from the non-irradiated area to ​​the irradiated one and can’t propagate in the opposite direction . This model is similar to the behavior of a semiconductor diode and describes the main mechanism for the formation of a circulating (spiral) wave. A modeling of of spiral waves drift in a gradient of excitability in the monolayer of cardiomyocytes is based on the critical degrees of excitation determined in the first model. For example, with  20%-intensive UV exposure the conduction velocity drops by 1.7 times compared to 100% exposure. Spiral wave, formed in such gradient of excitability, drifts more frequently towards lower excitability. Computer simulations employed  Aliev-Panfilov model with the two-fold difference in speed have shown  similar behavior of the rotating wave (figure 1).