Clustering of sodium channels at the neuromuscular junction.

Voltage-gated sodium channels (NaChs) are highly concentrated in the postsynaptic region of the neuromuscular junction, especially in the depths of postsynaptic folds and in the perijunctional region. The formation of the high NaCh density occurs during synapse maturation, approximately 2 weeks after initial synaptic contact in the rodent. The concentration of NaChs and their localization in the troughs of the folds increase the safety factor for neuromuscular transmission by reducing the threshold for initiation of the action potential. There is evidence that agrin plays a role in the formation of NaCh aggregation. Molecules such as ankyrin and syntrophin that bind NaChs may be important for maintenance of the high channel density at the endplate. Copyright 2000 Wiley-Liss, Inc.