Voltage-dependent calcium channel

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+. These channels are slightly permeable to sodium ions, so they are also often called "Ca2+-Na+ channels", but their permeability to calcium is about 1000-fold greater than to sodium under normal physiological conditions.

Structure

VDCCs are formed as a complex of several different subunits: α1, α2δ, β1-4 and γ. The α1 subunit forms the ion conducting pore while the associated subunits have several functions including the regulation of gating and modulation of the channel's activity.

Types

There are several types of VDCCs, classified according to the voltage at which they activate:

• L-type channels (Long-lasting)
• P/Q-type channels (Purkinje / Quality)
• N-type channels (Neural)
• R-type channels (Residual)
• T-type channels (Transient)

Function

VDCCs play a crucial role in both neurons and muscle cells. They are responsible for the influx of calcium ions into the cell, which initiates a series of events including muscle contraction, neurotransmitter release, gene expression, and cell death.

Clinical significance

Abnormalities in VDCC function can lead to a variety of diseases, such as hypertension, cardiac arrhythmia, and migraine. Certain drugs, like calcium channel blockers, are used to prevent the opening of these channels and thus treat these conditions.

See also

• Ion channel
• Voltage-gated ion channel
• Calcium channel blocker