a potent blocker of voltage-sensitive K⁺ channels; also blocks the Ca^2+-activated K⁺ channels; induces GABA release in synaptosomes.

60-amino acid polypeptide, with 3 disulfide bridges from Dendroaspis polylepis polylepis snake venom.

• Molecular Weight : 7,218 Da.
  
  
• Solubility in : Soluble in water.
  
  
• Purity min. : 97% (HPLC, mass spectrometry).
  
  
• Biological Activity : Potent inhibitor of various types of voltage-sensitive K⁺ channels. Inhibits the K⁺ channels at the pre and post-synaptic level in the intestinal smooth muscle [1]. It also inhibits Ca^2+-sensitive K⁺ channels from rat skeletal muscle, incorporated into planar bilayers (Kd = 90 nM in 50 mM KCl). DTX-I would not affect the Ca²⁺ or voltage dependence of gating [3].
  Like b-BuTX, it affects neurotransmission at the neuromuscular junction by an interaction with pre-synaptic nerve terminals [2]. Potent convulsant when administered intracerebro-ventricularly [1].
  nM ranges induce GABA release from brain synaptosomes [1].
  
  
• Toxicity (LD₅₀) : mice (i.p.): > 4 mg/kg.
  mice (i.c.): 8 µg/kg.
  
  
• Storage recommendations : store in saline.
  
  
• CAS Reg. No. : 107950-33-4
  
  
• Bibliography :
  
  1. Schweitz et al., "Purification and pharmacological characterization of peptide toxins from the black mamba (Dendroaspis polylepis) venom." Toxicon (1990). 28(7):847-856
  2. Rehm et al., "Existence of different populations of the DTXi binding protein associated with neuronal K⁺ channels." Biochem. and Biophys. Res. Com. (1988). 153(1): 231-240
  3. Lucchesi et al., "Subconductance behavior in a maxi Ca^2+-activated K⁺ channel induced by Dendrotoxin-I." Neuron, vol. 4, January, 1990.