SNX-482 is a peptide originally isolated from H. gigas venom that acts as a class E/R-type voltage-sensitive calcium channel blocker (IC50 = 30 nM in 192C cells expressing human class E channels).[1] It is selective for class E/R-type over class A and class B calcium channels (IC50s = >280 and ~800 nM, respectively), as well as the voltage-gated potassium channels Kv1.1, Kv1.2, and Kv1.4 (IC50s = >140 nM for all). SNX-482 inhibits class E/R-type calcium currents in isolated rat posterior pituitary (IC50 = 4 nM), however, it has no effect on class E/R-type calcium currents in isolated rat granule cells, retinal ganglion cells, or hippocampal pyramidal cells at concentrations up to 200 nM. Intrathecal administration of SNX-482 (0.5 µg/animal) inhibits formalin-induced neurokinin-1 (NK1) receptor internalization and cfos expression in the ipsilateral dorsal horn and reduces formalin-induced paw flinching in rats.[2]
References:
[1].Newcomb, R., Chen, X., Dean, R., et al.SNX‐482: A novel class E calcium channel antagonist from tarantula venomCNS Drug Rev.6(2)153-173(2000).
[2].Terashima, T., Xu, Q., Yamaguchi, S., et al.Intrathecal P/Q- and R-type calcium channel blockade of spinal substance P release and c-Fos expressionNeuropharmacology751-8(2013).