Journal of Neuroscience, Vol 6, 673-680, Copyright © 1986 by Society for Neuroscience
Localization of acetylcholine receptors and cholinesterase on nerve- contacted and noncontacted muscle cells grown in the presence of agents that block action potentials
DF Davey and MW Cohen
The possible role of nerve activity in triggering changes in the
localization of acetylcholine receptors (AChRs) and cholinesterase (ChE) on
nerve-contacted Xenopus muscle cells has been assessed. The localization of
these molecules was examined on nerve-contacted and noncontacted muscle
cells in cultures of spinal cord and myotomal muscle derived from Xenopus
embryos. Sites of high AChR density were revealed by staining with
fluorescent alpha-bungarotoxin and sites of ChE localization were revealed
histochemically. Localization of AChRs and ChE at sites of nerve-muscle
contact occurred when the culture medium contained 1.2 micron tetrodotoxin
(TTX), 1.2 micron TTX, 10 mM magnesium, and no calcium salts, 1.2 micron
TTX and 2 mM manganese, or 106 mM potassium methyl sulfate instead of
sodium chloride. The nerve- contacted muscle cells in each of these
modified culture media also exhibited a reduced incidence of AChR and ChE
patches away from the site of contact. It is concluded that the neural
factor(s) that triggers the local and remote changes in AChR and ChE
distribution can be supplied to the neurites and externalized in the
absence of nerve impulses, and that the nerve and muscle cells can interact
even when they are largely depolarized.