Free calcium ion pool (null)

The free calcium ions pool refers to the instantaneous concentration of unbound calcium ions (Ca²⁺) within a cellular compartment, primarily the cytosol, though similar pools exist in other compartments such as the mitochondria and the Golgi apparatus[2][4]. It acts as a key second messenger in diverse signal transduction pathways, regulating processes such as muscle contraction, neurotransmitter release, metabolism, cell cycle progression, and apoptosis[3][7]. The free calcium ion concentration is tightly controlled by channels, pumps, transporters, buffers, and intracellular stores; dysregulation is associated with cell injury, disease, and toxicity[5]. Unlike classic molecular targets, the free calcium pool is a physiological quantity, not a discrete protein or molecule, making it an indicator or mediator rather than a therapeutic target in the usual sense. Therapeutics modulate this pool indirectly by acting on channels, stores, transporters, or buffers.

Other names

cytosolic free calciumintracellular free calcium concentration ([Ca²⁺]ᵢ)cytosolic Ca²⁺free Ca²⁺ pool

Inhibition of calcium influx (by blocking channels, lowers cytosolic free calcium); Chelation of free calcium (binding/reducing free Ca²⁺ chemically); Modulation of release from intracellular stores; Enhancement of calcium efflux or uptake into stores