Fig. 1

Schematic representation of the ionic channels, pump, and exchanger in the CRN model. I _b,Ca background Ca²⁺ current, I _Ca,L L-type Ca²⁺ current, I _NaK Na⁺/K⁺ pump current, I _p,Ca sarcolemmal Ca²⁺ pump current, I _NaCa Na⁺/Ca²⁺ exchanger current, I _Na fast inward Na⁺ current, I _b,Na background Na⁺ current, I _Kr rapid component of delayed rectifier K⁺ current, I _Kur ultra-rapid component of delayed rectifier K⁺ current, I _Ks slow component of delayed rectifier K⁺ current, I _to transient-outward K⁺ current, I _K1 inward rectifier K⁺ current. The squares illustrate ionic channels and transporters (only for I _up and I _p,Ca), and circles illustrate ionic exchangers. The empty symbols correspond to channels and Na⁺/Ca⁺ exchanger that do not require ATP, and the filled symbols correspond to ionic transporters and Na⁺/K⁺ pump that require ATP. E1 transmembrane domain in KCNE1, S1–S6 transmembrane segments in KCNQ1, and P P-loop in KCNQ1