Tetrodotoxin binding to normal depolarized frog muscle and the conductance of a single sodium channel.

Wolfhard Almers, S. R. Levinson

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

1. We have examined the binding of tritium‐labelled and unlabelled tetrodotoxin to frog twitch muscle. Bio‐assay as well as radioisotope experiments show a saturable component of tetrodotoxin binding with a binding capacity of about 22 p‐mole/g wet wt., and a dissociation constant of about 5 nM. 2. If the observed uptake of tetrodotoxin by muscles represents one‐to‐one binding of the drug to sodium channels, the channel density is about 380 channels/mum2 of a muscle fibre's surface membrane. On the basis of this result and electrical measurements of sodium conductance in frog muscle, we calculate that the conductance of a single sodium channel is of the order of 10(−12) reciprocal ohms. This is one to two orders of magnitude less than previous estimates. 3. We have looked for an effect of membrane depolarization on saturable tetrodotoxin binding, and have found none. This suggests that there is little molecular interaction between the “gating” portion of the sodium channel molecule, and that which binds tetrodotoxin.

Original languageEnglish (US)
Pages (from-to)483-509
Number of pages27
JournalJournal of Physiology
Volume247
Issue number2
DOIs
StatePublished - May 1 1975
Externally publishedYes

Fingerprint

Sodium Channels
Tetrodotoxin
Anura
Muscles
Membranes
Radioisotopes
Biological Assay
Sodium
Pharmaceutical Preparations

ASJC Scopus subject areas

  • Physiology

Cite this

Tetrodotoxin binding to normal depolarized frog muscle and the conductance of a single sodium channel. / Almers, Wolfhard; Levinson, S. R.

In: Journal of Physiology, Vol. 247, No. 2, 01.05.1975, p. 483-509.

Research output: Contribution to journalArticle

@article{5d03f0286b5440fbbb0eddb4b1235c50,
title = "Tetrodotoxin binding to normal depolarized frog muscle and the conductance of a single sodium channel.",
abstract = "1. We have examined the binding of tritium‐labelled and unlabelled tetrodotoxin to frog twitch muscle. Bio‐assay as well as radioisotope experiments show a saturable component of tetrodotoxin binding with a binding capacity of about 22 p‐mole/g wet wt., and a dissociation constant of about 5 nM. 2. If the observed uptake of tetrodotoxin by muscles represents one‐to‐one binding of the drug to sodium channels, the channel density is about 380 channels/mum2 of a muscle fibre's surface membrane. On the basis of this result and electrical measurements of sodium conductance in frog muscle, we calculate that the conductance of a single sodium channel is of the order of 10(−12) reciprocal ohms. This is one to two orders of magnitude less than previous estimates. 3. We have looked for an effect of membrane depolarization on saturable tetrodotoxin binding, and have found none. This suggests that there is little molecular interaction between the “gating” portion of the sodium channel molecule, and that which binds tetrodotoxin.",
author = "Wolfhard Almers and Levinson, {S. R.}",
year = "1975",
month = "5",
day = "1",
doi = "10.1113/jphysiol.1975.sp010943",
language = "English (US)",
volume = "247",
pages = "483--509",
journal = "Journal of Physiology",
issn = "0022-3751",
publisher = "Wiley-Blackwell",
number = "2",

}

TY - JOUR

T1 - Tetrodotoxin binding to normal depolarized frog muscle and the conductance of a single sodium channel.

AU - Almers, Wolfhard

AU - Levinson, S. R.

PY - 1975/5/1

Y1 - 1975/5/1

N2 - 1. We have examined the binding of tritium‐labelled and unlabelled tetrodotoxin to frog twitch muscle. Bio‐assay as well as radioisotope experiments show a saturable component of tetrodotoxin binding with a binding capacity of about 22 p‐mole/g wet wt., and a dissociation constant of about 5 nM. 2. If the observed uptake of tetrodotoxin by muscles represents one‐to‐one binding of the drug to sodium channels, the channel density is about 380 channels/mum2 of a muscle fibre's surface membrane. On the basis of this result and electrical measurements of sodium conductance in frog muscle, we calculate that the conductance of a single sodium channel is of the order of 10(−12) reciprocal ohms. This is one to two orders of magnitude less than previous estimates. 3. We have looked for an effect of membrane depolarization on saturable tetrodotoxin binding, and have found none. This suggests that there is little molecular interaction between the “gating” portion of the sodium channel molecule, and that which binds tetrodotoxin.

AB - 1. We have examined the binding of tritium‐labelled and unlabelled tetrodotoxin to frog twitch muscle. Bio‐assay as well as radioisotope experiments show a saturable component of tetrodotoxin binding with a binding capacity of about 22 p‐mole/g wet wt., and a dissociation constant of about 5 nM. 2. If the observed uptake of tetrodotoxin by muscles represents one‐to‐one binding of the drug to sodium channels, the channel density is about 380 channels/mum2 of a muscle fibre's surface membrane. On the basis of this result and electrical measurements of sodium conductance in frog muscle, we calculate that the conductance of a single sodium channel is of the order of 10(−12) reciprocal ohms. This is one to two orders of magnitude less than previous estimates. 3. We have looked for an effect of membrane depolarization on saturable tetrodotoxin binding, and have found none. This suggests that there is little molecular interaction between the “gating” portion of the sodium channel molecule, and that which binds tetrodotoxin.

UR - http://www.scopus.com/inward/record.url?scp=0016735801&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0016735801&partnerID=8YFLogxK

U2 - 10.1113/jphysiol.1975.sp010943

DO - 10.1113/jphysiol.1975.sp010943

M3 - Article

C2 - 1080198

AN - SCOPUS:0016735801

VL - 247

SP - 483

EP - 509

JO - Journal of Physiology

JF - Journal of Physiology

SN - 0022-3751

IS - 2

ER -