Jingzhaotoxin-V, a 29-residue polypeptide, is derived from the venom of the spider Chilobrachys jingzhao. Jingzhaotoxin-V inhibits tetrodotoxin-resistant and tetrodotoxin-sensitive sodium currents in rat dorsal root ganglion neurons with IC 50 values of 27.6 nM and 30.2 nM, respectively. Jingzhaotoxin-V also inhibits Kv4.2 potassium currents expressed in Xenpus Laevis oocytes ( IC 50 of 604.2 nM).