Role of connectivity and fluctuations in the nucleation of calcium waves in cardiac cells
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Spontaneous calcium release (SCR) occurs when ion channel fluctuations lead to the nucleation of calcium waves in cardiac cells. This phenomenon is important since it has been implicated as a cause of various cardiac arrhythmias. However, to date, it is not understood what determines the timing and location of spontaneous calcium waves within cells. Here, we analyze a simplified model of SCR in which calcium release is modeled as a stochastic processes on a two-dimensional network of randomly distributed sites. Using this model we identify the essential parameters describing the system and compute the phase diagram. In particular, we identify a critical line which separates pinned and propagating fronts, and show that above this line wave nucleation is governed by fluctuations and the spatial connectivity of calcium release units. Using a mean-field analysis we show that the sites of wave nucleation are predicted by localized eigenvectors of a matrix representing the network connectivity of release sites. This result provides insight on the interplay between connectivity and fluctuations in the genesis of SCR in cardiac myocytes
CitationHernadez-Hernandez, G., Alvarez-Lacalle, E., Shiferaw, Y. Role of connectivity and fluctuations in the nucleation of calcium waves in cardiac cells. "Physical review E: statistical, nonlinear, and soft matter physics", 20 Novembre 2015, vol. 92, núm. 052715.