Fig 3. [Na⁺]_i levels at increasing frequencies.

Demonstration of intracellular Na⁺ levels ([Na⁺]_i during maneuvers that form the basis of this paper. Each in silico test involved the application of 1000 stimuli applied at a rate of 1 Hz (left) and then 2 Hz (right). This maneuver was done under baseline conditions (black) and also after increasing I_NaL 5-fold (red). Effects on [Na⁺]_i are shown in Panel A. The remaining data sets correspond to 50% inhibition of I_NaK (discontinuous black curve) and 50% inhibition of I_NaK and 5-fold increase of I_NaL (discontinuous red curve) in Panel B. In Panel C the black dotted curve corresponds to a 2-fold increase in I_NCX, and the dotted red curve corresponds to a 2-fold increase in I_NCX and a 5-fold increase in I_NaL.