Tityustoxin effect on nerve compound action potentials requires extracellular sodium.
Previous studies have demonstrated that Li(+) ions can substitute for Na(+) in a variety of functional systems. Using the single sucrose-gap recording technique, we measured the nerve compound action potential to study the effects of tityustoxin (an alpha-scorpion toxin that selectively inhibits fast Na(+) channel inactivation) upon removal of extracellular Na(+). Our results suggest that tityustoxin requires the presence of extracellular Na(+) to produce its typical pharmacological effect on Na(+) channel inactivation kinetics, but not to bind to its site.
Cruz
J S
JS
Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Caixa Postal 486, CEP 30161-970, Belo Horizonte, Minas, Gerais, Brazil. cruz@umbi.umd.edu
Matavel
A C
AC
Leão-Filho
H M
HM
Moraes-Santos
T
T
Beirão
P S
PS
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D005110:Extracellular Space / Q000378:metabolism*; D066298:In Vitro Techniques; D009498:Neurotoxins / Q000494:pharmacology*; D011892:Rana catesbeiana; D012584:Sciatic Nerve / Q000187:drug effects* / Q000502:physiology; D012604:Scorpion Venoms / Q000494:pharmacology*; D012964:Sodium / Q000378:metabolism*; D026941:Sodium Channel Blockers
D009498:Neurotoxins; D012604:Scorpion Venoms; D026941:Sodium Channel Blockers; C003609:tityustoxin; D012964:Sodium