Voltage-gated sodium channels represent the chemical (or molecular) level of structural organization in muscle sarcolemma.
Chemical level of structural organization is the first and the simplest level within the structural hierarchy. It includes the smallest unit of any of elements-atom, which combine to form molecules and macromolecules which also combine to form organelles, the functioning units of a cell. Sodium channels are membrane proteins which means that they are macromolecules.