PMID: 493Oct 1, 1975

The influence of pH on the rate of tetrodotoxin action on myelinated nerve fibres

The Journal of Physiology
W Ulbricht, H H Wagner


1. The experiments were done on single myelinated nerve fibres of Rana esculenta. The rates of toxin effect were studied either by measuring the maximum rate of rise, VA, of repetitively evoked action potentials or by measuring Na currents during periodic impulses in the voltage clamp. 2. VA measurements showed that in alkaline solutions (pH up to 8-8) the offset rate was unchanged while the onset was slowed in quantitative agreement with an assumed decrease in the active cationic form of tetrodotoxin. 3. Both VA measurements and those in the voltage clamp revealed a decrease in T'off, the offset time constant and in increase in the onset time constant, T'on, as the pH was lowered. 4. For tetrodotoxin concentrations, [TTX], up to 400 nM and pH values down to 5-3 the simple relation T'on/T'off = p'R held, where p'T is the constant factor by which the Na permeability was reduced at equilibrium with a given [TTX]. 5. The agreement between kinetic and equilibrium results was also valid when, at constant [TTX] and pH. p'T was modified by the holding potential during equilibration. 6. No unequivocal explanation of the results can be given but some of their features resemble acid catalysis.


Dec 1, 1991·Pflügers Archiv : European journal of physiology·G Hansen, W Ulbricht
Jan 1, 1986·Annals of the New York Academy of Sciences·G R StrichartzC H Bay
Jan 1, 1986·Annals of the New York Academy of Sciences·V L SalgadoT Narahashi
Jan 1, 1986·Annals of the New York Academy of Sciences·W UlbrichtJ Schmidtmayer
Jan 1, 1985·Pflügers Archiv : European journal of physiology·K M Gülden, W Vogel
Apr 15, 2010·Marine Drugs·Harry A Fozzard, Gregory M Lipkind
Sep 29, 1975·Pflügers Archiv : European journal of physiology·H H Wagner, W Ulbricht

Related Concepts

Nerve Impulses
Cell Membrane Permeability
Hydrogen-Ion Concentration
Myelinated Nerve Fiber
Rana esculenta
Ranvier's Nodes

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