Effect of Ca2+ Efflux Pathway Distribution and Exogenous Ca2+ Buffers on Intracellular Ca2+ Dynamics in the Rat Ventricular Myocyte: A Simulation Study
Figure 1
Schematic diagram of the rat ventricular cell compartmental model used in the present study. The description of the electrical activity of surface membrane (s, ds at surface dyads) and t-tubular membrane (t, dt at t-tubular dyads) comprises formulations of the following ion currents: fast sodium current (), L-type calcium current (), transient outward potassium current (), steady-state outward potassium current (), inward rectifying potassium current (), hyperpolarization-activated current (), background currents (, , and ), sodium-calcium exchange current (), sodium-potassium pump current (), and calcium pump current (). The intracellular space contains the cytosolic space (c), surface and t-tubular subsarcolemmal spaces (ss, st), surface and t-tubular dyadic spaces (ds, dt), network and junctional compartments of sarcoplasmic reticulum (NSR, JSRs, and JSRt), endogenous buffers (calmodulin (Bcm), troponin (Bhtrpn, Bltrpn), and calsequestrin (Bcs)), and exogenous buffer (e.g., BAPTA or EGTA (Bext)). Bts denotes the nonspecific buffer associated with luminal part of t-tubular membrane. represents flow via SR pump and the small filled rectangles in JSR membrane ryanodine receptors. The small bidirectional arrows denote diffusion. Ion diffusion between the t-tubular and extracellular spaces is represented by the dashed arrow. The changes with respect to the previous model [13] are highlighted in red. The Matlab code of the model can be downloaded at: http://www.it.cas.cz/en/d3/l033/biophysics-cardiac-cells.
