Voltage-gated calcium channel

Voltage-gated calcium channels (VGCCs), also known as voltage-dependent calcium channels (VDCCs), are a group of voltage-gated ion channels found in the membrane of excitable cells (e.g., muscle, glial cells, neurons, etc.) with a permeability to the calcium ion Ca²⁺.^[1][2] These channels are slightly permeable to sodium ions, so they are also called Ca²⁺–Na⁺ channels, but their permeability to calcium is about 1000-fold greater than to sodium under normal physiological conditions.^[3]

At physiologic or resting membrane potential, VGCCs are normally closed. They are activated (i.e.: opened) at depolarized membrane potentials and this is the source of the "voltage-gated" epithet. The concentration of calcium (Ca²⁺ ions) is normally several thousand times higher outside the cell than inside. Activation of particular VGCCs allows a Ca²⁺ influx into the cell, which, depending on the cell type, results in activation of calcium-sensitive potassium channels, muscular contraction,^[4] excitation of neurons, up-regulation of gene expression, or release of hormones or neurotransmitters.

VGCCs have been immunolocalized in the zona glomerulosa of normal and hyperplastic human adrenal, as well as in aldosterone-producing adenomas (APA), and in the latter T-type VGCCs correlated with plasma aldosterone levels of patients.^[5] Excessive activation of VGCCs is a major component of excitotoxicity, as severely elevated levels of intracellular calcium activates enzymes which, at high enough levels, can degrade essential cellular structures.