Excitation-contraction coupling

Excitation-contraction coupling is the sequence by which an electrical change in a muscle cell triggers calcium-dependent activation of its contractile machinery.

Action potential: A rapid, transient change in a cell’s membrane voltage that propagates along excitable membranes. The muscle-cell action potential initiates the events that release activating calcium.
Sarcoplasmic reticulum: A specialized membrane network in muscle cells that stores and releases calcium. It supplies the calcium that links electrical excitation to contraction.
Skeletal muscle: Striated muscle attached to the skeleton that produces voluntary movement and posture. Its coupling uses mechanical communication between voltage sensors and calcium-release channels.
Malignant hyperthermia: A life-threatening reaction to certain anesthetics, often involving uncontrolled calcium release in skeletal muscle. Mutations in calcium-release machinery can drive sustained contraction and heat production.
T-tubule: An inward extension of the muscle-cell membrane that carries electrical signals deep into the cell. T-tubules bring the action potential close to internal calcium stores.
Triad (muscle physiology): A skeletal-muscle structure formed by a T-tubule flanked by two terminal cisternae of the sarcoplasmic reticulum. This close arrangement enables voltage-triggered calcium release at a defined site.
Cardiac muscle: Striated muscle in the heart whose coordinated contractions pump blood. Its coupling depends on calcium entry triggering additional calcium release.
Central core disease: An inherited congenital myopathy commonly associated with variants in the skeletal-muscle ryanodine receptor gene. It links defective calcium handling to weakness and characteristic muscle pathology.
Dihydropyridine receptor: A voltage-sensitive L-type calcium channel in the transverse-tubule membrane, also called CaV1.1 in skeletal muscle. In skeletal muscle, voltage-sensing by this channel mechanically opens the ryanodine receptor.
Calcium-induced calcium release: A process in which calcium entering or present in a cell triggers further calcium release from intracellular stores. It is the key calcium-release mechanism in cardiac muscle, unlike skeletal muscle’s direct voltage coupling.

Linked from 13 pages