Figure 4.

Involvement of mitochondrial Ca²⁺ fluxes in simulations of Ca²⁺ oscillations. (A) Schematic representation of the Ca²⁺ exchanges processes between the three main cellular Ca²⁺ compartments: the cytosol, the mitochondria and the endoplasmic reticulum (ER). IP₃R: IP₃ receptor; MCU: mitochondrial Ca²⁺ uniporter; NCX: Na⁺/Ca²⁺ exchanger; SERCA: sarco- or endoplasmic reticulum Ca²⁺ ATPase. (B) Numerical simulations of Ca²⁺ oscillations in a model including mitochondrial Ca²⁺ fluxes (blue and green traces) and in a model that does not consider this organelle (red trace). Given the small volume of mitochondria, mitochondrial Ca²⁺ fluxes are quite irregular, which impacts on the variability of the interspike interval. Note, however, that the amplitude of the oscillations is stabilized in the presence of mitochondria. (C) Statistical analysis of the interspike interval when considering (blue) or neglecting (red) mitochondrial Ca²⁺ fluxes. Boxes indicate the first quartiles of the distributions and bars inside the box, the median values. Interspike intervals are normalized with respect to the corresponding deterministic value. See Wacquier et al. (2016, 2017) for details.