Isoform-specific effects of a novel BmK 11(2) peptide toxin on Na channels

Andrei Kondratiev, Richard Hahin, Gordon F. Tomaselli

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


BmK 11(2) is a 7216Da polypeptide toxin purified from the venom of the scorpion Buthus martensii Karsch. Nanomolar concentrations of the toxin prolong amphibian nerve action potentials without attenuation of the amplitude. The pharmacological action of the toxin and its sequence similarity to other α-scorpion toxins suggest that BmK 11(2) selectively alters voltage-gated Na channels. In order to test whether BmK 11(2) preferentially modulates the gating or kinetics of certain channel isoforms, we applied BmK 11(2) to muscle, heart and neuronal Na channels. 100nM BmK 11(2) increased the peak current amplitude of skeletal muscle (μ1) and neuronal (N1E-115) Na currents by 40 and 20%, respectively, and reduced the cardiac Na (hH1) current by 15%. The toxin slowed current decay of all isoforms, most prominently in N1E-115 (τBmKControl=12), μ1 (11), and less so for hH1 (1.3). BmK 11(2) shifted the voltage dependence of activation of μ1 and N1E-115 currents. BmK 11(2) had no effect on steady-state inactivation, use-dependent availability, and the kinetics of entry into slowly recovering inactivated states.

Original languageEnglish (US)
Pages (from-to)269-276
Number of pages8
Issue number3
StatePublished - Mar 1 2003
Externally publishedYes


  • BmK 11(2)
  • Na channel isoforms
  • Scorpion Buthus martensii Karsch

ASJC Scopus subject areas

  • Toxicology


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