Figure 8

Stability of the model and characteristics of the CaMK-dependent calcium dynamics. (A) Intracellular Na⁺ and K⁺ concentrations drift during a normal pacing stimulation at 1 Hz with the original Bondarenko model [53] and the model actually never stabilizes to physiological steady-state. Table 1 shows the corresponding values obtained with the developed model. (B) In the original Bondarenko model the removal fractions of NCX and PMCA were distorted reversely; see also Table 2. (C) Inclusion of the CaMK-dependent regulation of the calcium transport mechanisms enhances the positive dependence of systolic calcium (open symbols) on the pacing frequency. It also limits the excess rise of diastolic calcium (closed symbols) with high pacing frequencies, in line with the experimental findings (see Figure 2B).