Fig. 6.
Transmembrane voltage (Vm; A), free intracellular Ca2+ concentration ([Ca2+]i; B), percentage of regulatory units with strongly bound cross-bridges (XBs; C), and [Ca2+]troponin (D) plotted over time for our right atrial (RA) electromechanical myocyte models with chronic atrial fibrillation (cAF)-induced ionic remodeling. The final two beats (of the 74 total beats) isometrically paced at a sarcomere length (SL) of 1.9 µm with cAF-induced myofilament remodeling with a value of kon = 150% (blue lines), at a SL of 1.9 µm with kon = 225% (red lines), or at a SL of 2.3 µm with kon = 150% (green lines) are shown. The percentage of regulatory units (RUs) with strongly bound cross-bridges (XBs) were calculated as the sum of RUs in the XBPreR and XBPostR states divided by the total number of RUs.