Sensitivity of Tetrodotoxin

[Ernesto S. Ince]

CHINGWEN at PURCCVM.BITNET wrote:
: Hi!:
: Sorry, I think this is not a good question.
: Dose anyone out there know what's the sensitivity of tetrodotoxin (TTX)
: in hyperpolarized cells?
: What I try to say is
: If we pretreat cells with TTX, then followed by hyperpolarization.
: Does TTX still block Na channel effectively? any good ref?  Thanks!!!


If you give TTX and then give a drug that would have normally induced a 
response involving Na+ conductance, I believe the TTX effectively blocks 
the Na+. I would think the same would be true if you directly injected 
current into the cell. TTX is used to see what happens in the cell when 
you block transmission (action potentials), right? So if it wasn't very
effective at blocking that transmission people couldn't use it to see 
what is going on in the absence of action potentials.

Ernie