Fig. 1

Ionic membrane currents and intracellular calcium homeostasis in the TP + M model. Calcium currents: i_CaL—L-type Ca²⁺ current; i_bCa—background Ca²⁺ current. Potassium currents: i_K1—inward rectifier K⁺ current; i_to—transient outward current; i_Kr, i_Ks—rapid and slow delayed rectifier current; i_pK—plateau K⁺ current. Sodium currents: i_Na—fast Na⁺ current; i_bNa—background Na⁺ current. Pumps and exchangers: i_pCa—sarcolemmal Ca²⁺ pump current; i_NaK—Na⁺–K⁺ pump current; i_NaCa—Na⁺–Ca²⁺ exchanger (NCX) current. Calcium translocations: I_rel—Ca²⁺ release from the sarcoplasmic reticulum (SR) via ryanodine receptors to the subspace (SS); I_xfer—Ca²⁺ diffusion from SS to the cytoplasm; I_leak—a small Ca²⁺ leakage from the SR to the cytoplasm; I_up—Ca²⁺ pumping from the cytoplasm to the SR, where Ca²⁺ is partially buffered (Buffer in SR). Cytoplasmic buffering is divided into two compartments: Ca²⁺–troponin C complex formation (Ca–TnC) inherited from [28] and buffering by other intracellular ligands (Buffer). The figure is modified from the diagram in the Physiome Model Repository (https://models.physiomeproject.org/exposure/a7179d94365ff0c9c0e6eb7c6a787d3d/ten_tusscher_model_2006_IK1Ko_M_units.cellml/view) based on [20]