Inhibition of sodium channels in rat dorsal root ganglion neurons by Hainantoxin-IV, a novel spider toxin.
The effects of Hainantoxin-IV (HNTX-IV), a neurotoxic peptide isolated from the venom of the Chinese bird spider Seleconosmia hainana, on the adult rat dorsal root ganglion (DRG) neurons were investigated. Using the whole-cell patch-clamp technique HNTX-IV inhibited mammal neural TTX-sensitive (TTX-S) sodium currents evidently but the toxin failed to affect TTX-resistant (TTX-R) ones. The inhibition of HNTX-IV is dose-dependent with the IC(50) value of 44.6 nmol/L. The toxin didn't affect the activation and inactivation kinetics of sodium currents, but it caused a 10.1 mV hyperpolarizing shift in the voltage midpoint of steady-state sodium channel inactivation on DRG neurons. The results indicated that HNTX-IV, a novel spider toxin, maybe alternate voltage-gated sodium channels through a mechanism distinct from other spider toxins such as delta-ACTXs, mu-agatoxins I-VI which targeted the receptor site 3 to slow the inactivation kinetics of sodium currents.
Xiao
Yu-Cheng
YC
College of Life Sciences, Hunan Normal University, Changsha 410081, China.
Liang
Song-Ping
SP
D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005727:Ganglia, Spinal / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D015222:Sodium Channels / Q000187:drug effects* / Q000502:physiology; D013111:Spider Venoms / Q000633:toxicity*; D013779:Tetrodotoxin / Q000494:pharmacology
D015222:Sodium Channels; D013111:Spider Venoms; C474037:hainantoxin-IV, Seleconosmia hainana; D013779:Tetrodotoxin