Toxin and kinetic profile of rat brain type III sodium channels expressed in Xenopus oocytes

Brain Res Mol Brain Res. 1990 Feb;7(2):105-13. doi: 10.1016/0169-328x(90)90087-t.


Sodium (Na+) channels are members of a multigene family and are responsible for generation and propagation of the action potential in excitable cells. We have assembled, in a transcription-competent vector, a full-length cDNA clone encoding the rat brain type III Na+ channel. Xenopus oocytes microinjected with in vitro synthesized mRNA expressed functional rat brain Na+ channels from such 'cloned' RNA transcripts. We found that type III Na+ currents in whole cell microelectrode voltage clamp and in cell-attached patch recordings decayed much more slowly than any other reported Na+ current. In addition, we saw typical and additive effects of alpha- and beta-scorpion toxins, suggesting that the Na+ channel alpha-subunit itself contains functional and distinct toxin binding sites.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • DNA / metabolism
  • Electric Stimulation
  • Membrane Potentials / drug effects
  • Molecular Sequence Data
  • Neurotoxins / pharmacology
  • Oocytes / drug effects
  • Oocytes / metabolism
  • Oocytes / physiology*
  • RNA, Messenger / genetics*
  • RNA, Messenger / metabolism
  • Rats
  • Rats, Inbred Strains
  • Scorpion Venoms / pharmacology*
  • Sodium Channels / drug effects
  • Sodium Channels / metabolism
  • Sodium Channels / physiology*
  • Xenopus laevis


  • Neurotoxins
  • RNA, Messenger
  • Scorpion Venoms
  • Sodium Channels
  • DNA