A sodium channel is an ion channel that preferentially conducts sodium ions. In a voltage-gated sodium channel, changes in membrane potential control opening and inactivation. Under usual neuronal conditions, opening permits inward current that promotes depolarization, recruiting more voltage-gated sodium channels during the rising phase of an action potential. [ref]
Molecular Biology of the Cell, 4th edition by Bruce Alberts and others. Chapter 11, Voltage-Gated Ion Channels Generate Action Potentials in Electrically Excitable Cells
An illustrative current relation is , with an explicitly chosen sign convention. Even a large conductance produces little net current near the sodium reversal potential. Channel availability, opening and ionic driving force are therefore distinct. Inactivation also differs from merely closing a resting activation gate: recovery depends on the preceding voltage history.
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Sodium channels are a type of ion channel that are primarily responsible for the conduction of sodium ions (Na⁺) across cell membranes. These channels play a crucial role in various physiological processes, particularly in the generation and propagation of electrical signals in excitable tissues, such as neurons and muscle cells.
Base machinery of the nervous system.