Trypargine blocks the sodium channels only from the inside of squid giant axon.
A new tetrahydro-beta-carboline, trypargine (TRG), specifically suppresses the Na current (INa) when applied to the internal surface of the squid axon membrane without affecting the K current (IK). The binding of TRG to its receptor is potential-dependent and occurs at a site about halfway through the membrane electric field from the outside; the dissociation constant is 11 microM at 0 mV.
Seyama
I
I
Yakehiro
M
M
Nakajima
T
T
D000818:Animals; D001369:Axons / Q000378:metabolism*; D002243:Carbolines / Q000494:pharmacology*; D049832:Decapodiformes; D006706:Homeostasis; D007473:Ion Channels / Q000187:drug effects*; D012964:Sodium / Q000378:metabolism*
D002243:Carbolines; D007473:Ion Channels; C009804:tryptoline; D012964:Sodium