Sodium channels' kinetics under self-gating condition at neuromuscular junction

摘要

The neuromuscular junction (NMJ) is the synapse between the axon terminal of motoneuron and the ‘endplate’ of a muscle fiber. The nerve impulse leads to a large depolarization called the endplate potential, which in turn opens a large number of voltage-sensitive sodium channels located within post-junctional synaptic folds. This set off causing an ‘all or nothing’ action potential that is propagated along the muscle fiber and initiate muscle contraction. In this work we have simulated the behavior of the voltage-dependent sodium conductance within the NMJ using a mathematical model. We simulated sodium channels activation and inactivation kinetics under voltage clamp condition. We observed a self-gating behavior of the sodium conductance during activation and inactivation. The simulation results showed that self-gating of sodium channels increase conduction efficiency at the NMJ.