- Alomone Labs Huwentoxin-I inhibits NaV1.7 currents heterologously expressed in HEK-293 cells.A. Time course of Huwentoxin-I (#STH-050) blocking action on NaV1.7 currents. Maximum current amplitudes were plotted as a function of time. Membrane potential was held at -100 mV and cells were stimulated by a 20 ms voltage step to -30 mV. 200 nM Huwentoxin-I were perfused as indicated by the bar (green) during 350 sec. B. Superimposed examples of NaV1.7 channel current in the absence (control) and presence (green) of 200 nM Huwentoxin-I (taken from the experiment in A).
Huwentoxin-I (HwTx-I) is a 33-residue peptide toxin that was originally isolated from the venom of the Chinese bird spider (Ornithoctonus huwena). Huwentoxin-I is known to be an inhibitor of tetrodotoxin-sensitive voltage-gated Na+ channels (TTX-S) with IC50 values of ~50 nM and N-type voltage-sensitive Ca2+ channels with IC50 values of ~100 nM in mammalian DRG, hippocampus and insect DUM neurons1. It has only a very weak effect on L-type Ca2+ channels, no effect on TTX-R channels and has virtually no effect on muscle Na+ channels. The selectivity of Huwentoxin-I for Ca2+ channels appears to be higher than ω-conotoxin MVIIA and equivalent to ω-conotoxin GVIA2. Huwentoxin-I demonstrates an antinociceptive effect in the rat model of the formalin test when administrated intrathecally (ED50 ~0.28 µg/kg), without side effects of the ones caused by ω-conotoxin MVIIA3.
Huwentoxin-I also blocks neuromuscular transmission by acting on nAChR4.