title: Role of connectivity and fluctuations in the nucleation of calcium waves in cardiac cells.
abstract: 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.
authors.affiliation: Department of Physics & Astronomy, California State University, Northridge, 18111 Nordhoff Street, Northridge, CA 91330, USA.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Hernandez-Hernandez
authors.affiliation: Physics Department, Universitat Politècnica de Catalunya, BarcelonaTech, Barcelona, Spain.
authors.forename: Enric
authors.initials: E
authors.lastname: Alvarez-Lacalle
authors.affiliation: Department of Physics & Astronomy, California State University, Northridge, 18111 Nordhoff Street, Northridge, CA 91330, USA.
authors.forename: Yohannes
authors.initials: Y
authors.lastname: Shiferaw
mesh_terms: D020013:Calcium Signaling; D007473:Ion Channels / Q000378:metabolism; D008954:Models, Biological; D009206:Myocardium / Q000166:cytology* / Q000378:metabolism; D013269:Stochastic Processes
chemical_list: D007473:Ion Channels