Action potentials and sodium inward currents of developing neurons in Xenopus nerve-muscle cultures.
Action potentials and voltage-gated Na+ inward currents from cultured embryonic neurons of Xenopus laevis were recorded using the patch-clamp technique in the whole cell configuration. Neurons together with muscle cells were dissociated from embryos shortly after completion of gastrulation. Under the voltage-clamp condition the voltage-gated Na+ inward current was isolated from other currents by pharmacological means and by ion substitution. A small Na+ current was observed in round cells without neurites (presumptive neurons). The mean amplitude of the peak Na+ current was 2.5 times larger in neurons with short processes than in presumptive neurons. As they developed further by extending longer processes, the maximum amplitude of the Na+ inward current recorded at the soma decreased. In varicosities, the Na+ inward current density was greater than that at the soma of neurons with extended neurites but kinetic properties and voltage-dependency were similar.
Kidokoro
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Y
Jerry Lewis Neuromuscular Research Center, UCLA School of Medicine 90024.
Sand
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O
D000200:Action Potentials; D000818:Animals; D002478:Cells, Cultured; D009469:Neuromuscular Junction / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D015222:Sodium Channels / Q000502:physiology*; D014982:Xenopus laevis
D015222:Sodium Channels