Veratridine modifies the TTX-resistant Na+ channels in rat vagal afferent neurons.
A number of neurotoxins from venoms of invertebrates and plants are ligands for voltage-gated Na+ channels and are useful tools for studying Na+ channel function and structure. Using whole-cell recordings from vagal afferent nodose neurons, we studied neurotoxins that target Na+ channels. We asked whether Ts3 (an alpha-scorpion toxin) and/or veratridine (a lipid-soluble toxin), could modify the TTX-resistant Na+ current generated by vagal afferent nodose neurons. Nodose TTX-resistant current was not affected by Ts3, whereas Ts3 slowed inactivation of the current generated by TTX-sensitive current component. We found that veratridine inhibited the TTX-resistant Na+ currents on rat nodose neurons. Interestingly, veratridine-modified Na+ channels developed a persistent current that accounted for the large tail current observed. We propose that veratridine modifies TTX-resistant Na+ channels through a mechanism distinct from its actions on other voltage-gated Na+ channels.
Campos
Fabiana Vasconcelos
FV
Excitable Membranes Laboratory, Department of Biochemistry and Immunology, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antonio Carlos 6627, Belo Horizonte, MG CEP 31970-901, CP 486, Brazil.
Moreira
Thaís Helena
TH
Beirão
Paulo Sérgio Lacerda
PS
Cruz
Jader Santos
JS
D000818:Animals; D001693:Biological Transport, Active; D017136:Ion Transport / Q000187:drug effects; D008297:Male; D009475:Neurons, Afferent / Q000378:metabolism*; D009498:Neurotoxins / Q000378:metabolism / Q000633:toxicity*; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D012604:Scorpion Venoms / Q000378:metabolism / Q000633:toxicity*; D012964:Sodium / Q000378:metabolism*; D015222:Sodium Channels / Q000187:drug effects* / Q000378:metabolism; D013779:Tetrodotoxin; D014630:Vagus Nerve / Q000378:metabolism; D014701:Veratridine / Q000378:metabolism / Q000633:toxicity*
D009498:Neurotoxins; D012604:Scorpion Venoms; D015222:Sodium Channels; C485970:Ts3 toxin, Tityus serrulatus; D013779:Tetrodotoxin; D014701:Veratridine; D012964:Sodium