Voltage-gated ion channels are a class of ion channels that open or close in response to changes in the electrical potential across the cell membrane. These channels allow ions to flow into or out of the cell in response to changes in voltage and thus play a critical role in the electrical signaling of cells. Different types of voltage-gated ion channels are specific for other ions, such as sodium (Na_V), potassium (K_V), and calcium (Ca_V) channels, as well as hyperpolarization-activated cyclic nucleotide-gated channels (HCN) and Transient Receptor Potential (TRP) channels.

Voltage-gated sodium channels open in response to a depolarization of the cell membrane and allow the influx of positively charged sodium ions (Na⁺) into the cell. This influx of ions causes a further depolarization of the membrane, known as an action potential, which is the primary mechanism of electrical signaling in nerve and muscle cells.

Voltage-gated potassium channels open in response to depolarization and allow the efflux of positively charged potassium ions (K⁺) out of the cell. This efflux of ions causes a repolarization of the membrane, which helps to terminate the action potential and reset the cell for the following action potential.

Voltage-gated calcium channels open in response to depolarization and allow the influx of positively charged calcium ions (Ca²⁺) into the cell. This influx of ions is critical in regulating muscle contraction, neurotransmitter release, and gene expression.

Mutations in voltage-gated ion channels are linked to various diseases, including neurological disorders such as epilepsy and muscular dystrophy, and cardiac arrhythmias. Voltage-gated ion channels are also important drug targets for various diseases.