Sodium Channels

Synonyms

Voltage-dependent sodium (Na⁺) channel; Voltage-gated Na⁺ channel; Voltage-sensitive Na⁺ channel; Voltage-activated Na⁺ channel

Definition

Sodium (Na⁺) channels are membrane glycoproteins (Cell Membrane - Components and Functions) that form Na⁺-selective voltage-gated pores across the plasma membranes of excitable cells, such as neurons and muscle fibers. When these pores are in an open configuration, Na⁺ cations flow through them. This flux is usually into the cell, and thus creates a voltage change across the cell membrane that is the basis of the propagating electrical signal known as the action potential (Action potential; Action potential propagation). (Note: These voltage-gated channels are not to be confused with non-voltage-gated epithelial Na⁺ channels (ENaCs) that are found in a variety of epithelial tissues, such as kidney, colon, and lung.)

Characteristics

Voltage-gated Na⁺ channels are the primary molecular entities that initiate the propagating