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.

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 β-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].

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.