L-type calcium channel

L-type calcium channel is a type of voltage-gated calcium channel that plays a crucial role in the physiology of excitable cells. Named for their long-lasting open state, L-type calcium channels are responsible for the excitation-contraction coupling of skeletal, smooth, and cardiac muscle and for the regulation of other processes such as hormone secretion and gene expression.

Structure

L-type calcium channels are composed of several subunits: the α1, α2δ, β, and γ subunits. The α1 subunit forms the ion-conducting pore while the associated subunits have several functions including the regulation of gating and ion selectivity.

Function

L-type calcium channels are activated by membrane depolarization, which causes a conformational change in the channel and allows calcium ions to flow into the cell. This influx of calcium triggers a variety of cellular responses, including muscle contraction, hormone secretion, and gene expression.

In the heart, L-type calcium channels are responsible for the plateau phase of the action potential in cardiac myocytes, which is essential for the contraction of the heart muscle. In the brain, they contribute to the regulation of neuronal firing patterns and are involved in learning and memory.

Clinical significance

Mutations in the genes encoding the subunits of L-type calcium channels can lead to a variety of diseases, including hypertension, cardiomyopathy, and certain types of epilepsy. In addition, drugs that block L-type calcium channels, such as calcium channel blockers, are used to treat conditions such as hypertension and angina.

See also

• Voltage-gated calcium channel
• Calcium channel blocker
• Action potential