Improved Model of the Coupled Ca2+ and Sarcolemmal Voltage Clocks for Sinoatrial Node Cell
Abstract
In order to investigate the role of Ca2+ and sarcolemmal voltage clocks in arrhythmia quantitatively, a mathematical model about the two clocks in sinoatrial node cells (SANCs) is essential, but the current model lacks to present the electrophysiological heterogeneities. In the present paper, the novel central and peripheral SANC models were developed by considering differences of various current densities as well as the presence of Na+ current in the periphery. A one-dimensional (1D) model was also developed to reflect the differences in capacitance and conductance with the location. The simulation results show that the large amplitudes of L- and Ttype Ca2+ currents in periphery are the major contributors to great upstroke velocity of the action potential. The short cycle length in the peripheral SANC mainly attributes to the large rapid and slow delayed rectifying K+ currents. Isolated sarcoplasm reticulum is unable to persistently oscillate at low Ca2+ pumping rate, suggesting importance of the synergism of coupled Ca2+ and sarcolemmal voltage clocks. These characteristics of action potentials and major ionic currents, Ca2+ clock activities as well as the electrical conduction along the 1D tissue verify the efficiency of the improved models, thus indicating their promising applications in the study of the role of two clocks in various kinds of arrhythmia.
Keywords
Sinoatrial node cell, Mathematical modeling, Ca2+ clock; Voltage clock, Ionic currents, Computer simulations
DOI
10.12783/dteees/peem2016/5034
10.12783/dteees/peem2016/5034
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