Figure 3. Bifurcation analysis of the modifications of Ca²⁺ oscillations by store depletion.

(A) A typical bifurcation diagram of [Ca²⁺]_c against [IP₃] in IP₃-induced Ca²⁺ oscillations is presented. Steady-state solutions (solid line) and the maxima and the minima of [Ca²⁺]_c during Ca²⁺ oscillations (broken line) are shown. [Ca²⁺]_c will be stationary when [IP₃] is outside the ‘oscillatory’ area (1). [Ca²⁺]_c oscillates when [IP₃] is in the ‘oscillatory’ area, which is encompassed by the broken line (2 and 3). Oscillation frequency is faster at higher [IP₃] (3) than lower [IP₃] (2). (B) Bifurcation diagrams of [Ca²⁺]_c against [IP₃] in the whole-cell model. Steady-state solutions (solid line), the maxima and the minima of [Ca²⁺]_c during Ca²⁺ oscillations (broken line) are shown. S=200 μM in control and S=160 μM in depleted store.