Cardiac calcium handling machinery

The cardiac calcium handling machinery is a coordinated network of proteins and organelles that regulates the flux of calcium ions (Ca²⁺) within cardiomyocytes to drive the heartbeat [1, 5]. This system is central to excitation-contraction (E-C) coupling, where an action potential triggers calcium entry via L-type calcium channels (LTCC), which then stimulates a massive release of Ca²⁺ from the sarcoplasmic reticulum (SR) through ryanodine receptor 2 (RyR2) channels [3, 6]. This calcium-induced calcium release (CICR) activates the myofilaments to cause contraction [5, 11]. For relaxation to occur, Ca²⁺ must be rapidly removed from the cytosol, primarily by the sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA2a) pump and the sodium-calcium exchanger (NCX) [3, 12]. Dysregulation of these components—such as RyR2 leakiness or SERCA2a downregulation—is a primary driver of contractile dysfunction in heart failure and electrical instability in arrhythmias [1, 4, 8]. Consequently, the machinery is a major focus for drug development, with therapies ranging from traditional calcium channel blockers to novel RyR2 stabilizers (Rycals) and SERCA2a activators [2, 7, 12].

Other names

Excitation-contraction coupling machineryCardiac calcium handling systemIntracellular calcium cycling machineryCalcium handling proteins

Modulation of intracellular calcium cycling through inhibition of L-type calcium channels, stabilization of ryanodine receptors, activation of SERCA2a pumps, or inhibition of CaMKII signaling to restore calcium homeostasis and improve cardiac function.