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

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.