A Dynamic Model of Cytosolic Calcium Concentration Oscillations in Mast Cells

In this paper, a dynamic model of cytosolic calcium concentration () oscillations is established for mast cells (MCs). This model includes the cytoplasm (Cyt), endoplasmic reticulum (ER), mitochondria (Mt), and functional region (μd), formed by the ER and Mt, also with channels in these cellular compartments. By this model, we calculate oscillations that are driven by distinct mechanisms at varying (degradation coefficient of inositol 1, 4, 5-trisphosphate, and production coefficient of ), as well as at different distances between the ER and Mt (ER–Mt distance). The model predicts that (i) Mt and μd compartments can reduce the amplitude of oscillations, and cause the ER to release less during oscillations; (ii) with increasing cytosolic concentration (), the amplitude of oscillations increases (from 0.1 μM to several μM), but the frequency decreases; (iii) the frequency of oscillations decreases as the ER–Mt distance increases. What is more, when the ER–Mt distance is greater than 65 nm, the μd compartment has less effect on oscillations. These results suggest that Mt, μd, and can all affect the amplitude and frequency of oscillations, but the mechanism is different. The model provides a comprehensive mechanism for predicting cytosolic concentration oscillations in mast cells, and a theoretical basis for calcium oscillations observed in mast cells, so as to better understand the regulation mechanism of calcium signaling in mast cells.