Functional differences between 4-aminopyridine and tetraethylammonium-sensitive potassium channels in myelinated axons

Neurosci Lett. 1987 Mar 31;75(2):193-8. doi: 10.1016/0304-3940(87)90296-5.

Abstract

Intracellular recordings from rat sciatic nerve fibers showed that the potassium channel blocking agents 4-aminopyridine (4-AP) and tetraethylammonium (TEA) had different effects on action potential waveform. When applied alone, TEA did not appreciably alter the waveform of an individual action potential, whereas 4-AP application resulted in action potential broadening and, in some axons, repetitive firing. A prolonged afterhyperpolarization which was blocked by TEA occurred subsequent to repetitive firing. These results indicate the presence of at least two pharmacologically defined potassium channels in mammalian peripheral nerve fibers. The 4-AP-sensitive potassium channels are important for rapid action potential repolarization and the TEA-sensitive potassium channels may serve to modulate axonal excitability during repetitive firing.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 4-Aminopyridine
  • Action Potentials / drug effects
  • Aminopyridines / pharmacology*
  • Animals
  • Ion Channels / drug effects*
  • Ion Channels / physiology
  • Nerve Fibers, Myelinated / drug effects*
  • Nerve Fibers, Myelinated / physiology
  • Potassium / metabolism*
  • Rats
  • Rats, Inbred Strains
  • Sciatic Nerve / drug effects
  • Sciatic Nerve / physiology
  • Tetraethylammonium
  • Tetraethylammonium Compounds / pharmacology*

Substances

  • Aminopyridines
  • Ion Channels
  • Tetraethylammonium Compounds
  • Tetraethylammonium
  • 4-Aminopyridine
  • Potassium