Electric field-directed growth and branching of cultured frog nerves: effects of aminoglycosides and polycations

Lynda Erskine, R Stewart, Colin Darnley McCaig

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36 Citations (Scopus)


The direction and rate of earliest nerve growth are critical determinants of neuronal architecture. One extrinsic cue that influences these parameters is a small direct current electric field, although the underlying mechanisms are unclear. We have studied the orientation, rate of growth, and branching behavior of embryonic Xenopus spinal neurites exposed to aminoglycoside antibiotics, to raised external cations, to applied direct current electric fields, and to combinations of these treatments. Field-induced cathodal turning and cathodal branching of neurites were blocked by the aminoglycosides, by raised extracellular calcium ([Ca2+]0) and by raised extracellular magnesium ([Mg2+]0). Neomycin together with high external Ca2+, by contrast, induced a reversal in the polarity of turning and branching, with neurites reorienting and branching more frequently anodally. Aminoglycosides decreased neurite growth rates, and for neomycin this was partially reversed by high external Ca2+. Raised [Ca2+]0 alone but not raised [Mg2+]0 altered growth rates in a field-strength dependent manner. Modulation of membrane surface charge may underlie altered galvanotropic orientation and branching. Such an effect is insufficient to explain the changes in growth rates, which may result from additional perturbations to Ca2+ influx and inositol phospholipid metabolism.
Original languageEnglish
Pages (from-to)523-536
Number of pages14
JournalJournal of Neurobiology
Issue number4
Publication statusPublished - 1 Apr 1995


  • Animals
  • Anti-Bacterial Agents
  • Cations, Divalent
  • Cell Division
  • Cells, Cultured
  • Electromagnetic Fields
  • Membrane Potentials
  • Neomycin
  • Neurites
  • Spinal Cord
  • Xenopus laevis
  • Electrical field
  • Surface potential
  • neomycin
  • nerve branching
  • orientation


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