Toxin I from the snake Dendroaspis polylepis polylepis: a highly specific blocker of one type of potassium channel in myelinated nerve fiber

Brain Res. 1986 Jul 9;377(2):374-7. doi: 10.1016/0006-8993(86)90884-x.


Toxin I from the venom of the black mamba snake Dendroaspis polylepis polylepis specifically blocks one component of the K-current (IKf1) in the frog node of Ranvier, with a high affinity (Kd = 4 X 10(-10) M) without significantly affecting either the others components of the K current (IKf2 and IKs) or the Na-current. Moreover, for toxin concentrations corresponding to 10- or 100-fold the Kd value, the block was almost irreversible.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Depression, Chemical
  • Elapid Venoms / pharmacology*
  • In Vitro Techniques
  • Ion Channels / drug effects*
  • Potassium / metabolism*
  • Rana esculenta
  • Ranvier's Nodes / drug effects*
  • Sodium / metabolism


  • Elapid Venoms
  • Ion Channels
  • Sodium
  • Potassium