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J Neurosci February 1, 2000; 20 (3): 1020-9.

A role for voltage-gated potassium channels in the outgrowth of retinal axons in the developing visual system.

McFarlane S , Pollock NS .

Neural activity is important for establishing proper connectivity in the developing visual system. Tetrodotoxin blockade of sodium (Na(+))-dependent action potentials impairs the refining of synaptic connections made by developing retinal ganglion cells (RGCs), but does not affect their ability to get out to their target. Although this may suggest neural activity is not required for the directed extension of RGC axons, in many species developing RGCs express additional, Na(+)-independent ionic mechanisms. To test whether the ability of RGC axons to extend in a directed fashion is influenced by membrane excitability, we blocked the principal modulators of the neural activity of a neuron, voltage-dependent potassium (Kv) channels. First, we showed that RGCs and their growth cones express Kv channels when they are growing through the brain on the way to their main midbrain target, the optic tectum. Second, a Kv channel blocker, 4-aminopyridine (4-AP), was applied to the developing Xenopus optic projection. Blocking Kv channels inhibited RGC axon extension and caused aberrant routing of many RGC fibers. With the higher doses, <25% of embryos had a normal optic projection. These data suggest that Kv channel activity regulates the guidance of growing axons in the vertebrate brain.

PubMed ID: 10648707
PMC ID: PMC6774185
Article link: J Neurosci

Species referenced: Xenopus
Genes referenced: isl1 kcnd3 ncam1 tbx2 tec
Antibodies: Glia Ab2 Ncam1 Ab2 Nefm Ab1 Neuronal Ab1

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References [+] :
Arcangeli, Integrin-mediated neurite outgrowth in neuroblastoma cells depends on the activation of potassium channels. 1993, Pubmed