Motor nerve and skeletal muscle membrane potential (MP)

Motor nerve and skeletal muscle membrane potential refers to the electrical voltage difference across the plasma membranes of motor neurons and skeletal muscle fibers, which is essential for the transmission of nerve impulses and the initiation of muscle contraction (StatPearls, Physiology, Resting Potential, 2023). This potential is established by the selective permeability of the membrane to ions—primarily potassium, sodium, and chloride—and is maintained by the energy-dependent Na+/K+-ATPase pump (PubMed, PMC5021493). In motor nerves, the generation of an action potential allows for rapid signal transmission to the neuromuscular junction, where the release of acetylcholine triggers a localized depolarization of the muscle membrane (sarcolemmal potential). This depolarization propagates across the muscle fiber, leading to calcium release from the sarcoplasmic reticulum and subsequent mechanical contraction (NIH, Muscle Contraction, 2022). While not a single molecular target, the membrane potential is the functional endpoint for many pharmacological interventions, including local anesthetics that block voltage-gated sodium channels and neuromuscular blocking agents used to induce muscle relaxation during surgical procedures (PubChem, Lidocaine Compound Summary). Dysregulation of this potential leads to various neuromuscular disorders such as periodic paralysis or myasthenia gravis.

Other names

Resting membrane potentialAction potentialTransmembrane potentialSarcolemmal potentialAxonal potentialNeuromuscular excitability

Drugs modulate the membrane potential by altering the conductance of voltage-gated ion channels (e.g., Na+, K+) or by acting as agonists or antagonists at ligand-gated receptors (e.g., nAChR) at the neuromuscular junction, thereby shifting the electrical state of the cell (StatPearls, Physiology, Resting Potential, 2023; PubMed, PMID: 16102735).