Figure 3. The calcium frequency response (CFR) .

Rate‐dependent changes in peak [Ca²⁺]_i, diastolic [Ca²⁺]_i (DCa), magnitude of peak [Ca²⁺]_i relative variation (Δ_MPCa), and Ca²⁺ in the sarcoplasmic reticulum ([Ca²⁺]_SR) due to changes in the extracellular Ca²⁺ concentration ([Ca²⁺]_o). Each column represents a different model: the baseline model (DD), a model with inclusion of the CAMKII mediation of LCC and I _to activity (CAMK), a model with inhibition of the CAMKII‐mediated increase in SERCA activity (NO CAMK) and a model with reduced Na⁺/K⁺ affinity to Na⁺ (RNaK). Different colours represent different [Ca²⁺]_o: 1.0 mm (light grey), 1.4 mm (dark grey) and 1.8 mm (black).