Sodium channels are the main component and responsible for the rising phase of action potentials in excitable cells such as neurons, myocytes, and some certain types of glia. The dynamics of sodium channels can be classified into three different states: resting, active and inactive states.

Genetic mutations that cause persistent activity in sodium channels can cause disease by creating excessive activity of certain kinds of neurons. Mutations that interfere with Na⁺ channel inactivation can contribute to cardiovascular diseases or epileptic seizures by window currents, which can cause muscle and/or nerve cells to become over-excited.