Figure 2.

MCU localization on action potential and Ca²⁺ cycling properties under normal conditions. (A) Time courses of V, ${\overline{\left[C{a}^{2+}\right]}}_i$, ${\overline{\left[C{a}^{2+}\right]}}_{JSR}$, $\overline{\mathit{\Delta }\psi }$, ${\overline{\left[C{a}^{2+}\right]}}_m$, and ${\overline{\left[CaMKII\right]}}_{act}$ for MCU facing cytosol (black), submembrane space (red), and dyadic space (cyan), respectively, are shown. In the model, MCU only senses local Ca²⁺. For example, when the MCU faces cytosol, it only senses the local Ca²⁺ concentration in the corresponding cytosolic space, that is, [Ca²⁺]_i. Because MCU localization exhibits small effects on action potential and intracellular Ca²⁺ cycling properties, the colors are overlapped except in the panels for $\overline{\mathit{\Delta }\psi }$ and ${\overline{\left[C{a}^{2+}\right]}}_m$. (B) Mitochondrial free Ca²⁺ amplitude $\mathit{\Delta }{\overline{\left[C{a}^{2+}\right]}}_m$ for the three MCU localizations is shown. (C) Mitochondrial free Ca²⁺ in response to fast pacing is shown. Colored traces correspond to different MCU localizations. To see this figure in color, go online.