Depolarization-induced facilitation of a plateau-generating current in ventral horn neurons in the turtle spinal cord

J Neurophysiol. 1997 Sep;78(3):1740-2. doi: 10.1152/jn.1997.78.3.1740.


Plasticity at the neuronal level commonly involves use-dependent changes in strength of particular synaptic pathways or regulation of postsynaptic properties by modulatory transmitters. Here we analyze a novel form of short-term plasticity mediated by use-dependent facilitation of postsynaptic responsiveness. Using current- and voltage-clamp recordings, we found that all spinal ventral horn neurons able to generate plateau potentials showed depolarization-induced facilitation of the underlying inward current. Facilitation was noticeable when the neurons were depolarized to more than -50 mV at intervals <4 s. When stimulation with fast triangular voltage ramps was used, the inward current activated at a less depolarized potential during the second ramp. The inward current and facilitation was eliminated by nifedipine, a selective antagonist of L-type calcium channels. Depolarization-induced facilitation of low-voltage-activated L-type calcium channels is suggested to be the underlying mechanism. It is noted that facilitation occurs on a time scale compatible with a role in phasic motor activity.

MeSH terms

  • Animals
  • Anterior Horn Cells / drug effects
  • Anterior Horn Cells / physiology*
  • Calcium Channel Blockers / pharmacology
  • Electrophysiology
  • In Vitro Techniques
  • Interneurons / drug effects
  • Interneurons / metabolism
  • Ion Channels / drug effects
  • Ion Channels / physiology
  • Motor Neurons / drug effects
  • Muscarine / pharmacology
  • Muscarinic Agonists / pharmacology
  • Muscarinic Antagonists / pharmacology
  • Neuronal Plasticity / drug effects
  • Patch-Clamp Techniques
  • Spinal Cord / cytology
  • Spinal Cord / drug effects
  • Spinal Cord / physiology*
  • Turtles / physiology*


  • Calcium Channel Blockers
  • Ion Channels
  • Muscarinic Agonists
  • Muscarinic Antagonists
  • Muscarine