Differential effects of tetracaine on delayed potassium channels and displacement currents in frog skeletal muscle

Wolfhard Almers

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

Delayed K+ currents and displacement currents were studied with a voltage clamp technique. In normal fibres, the conductance of the delayed channel grows e fold per 3 millivolts at sufficiently negative potentials and reaches a limiting value of 2-10 m mho/cm2 (mean 5.8 m mho/cm2) at positive potentials. Adding tetracaine (2 mM) reduces the limiting conductance, shifts the voltage dependence of the delayed channel to +25 mV more positive potentials and slows the kinetics fourfold. By contrast, the displacement currents are virtually unaltered by 2 mM tetracaine. Their voltage dependence is shifted by less than 5 mV and their kinetics are unaffected. Tetraethylammonium ions (TEA) are known to slow the kinetics of delayed K+ channels fivefold but fail, like tetracaine, to change the kinetics of the displacement currents. Both tetracaine and TEA have thus large effects on the 'gating' of the delayed channel, yet little or none on the displacement currents. This suggests that the displacement currents in skeletal muscle are for the most part unrelated to the opening and closing of delayed channels. It is estimated that 'gating' the delayed channel in muscle may require no more than 1 or 2% of the observed charge displacement.

Original languageEnglish (US)
Pages (from-to)613-637
Number of pages25
JournalJournal of Physiology
Volume262
Issue number3
StatePublished - 1976
Externally publishedYes

Fingerprint

Tetracaine
Potassium Channels
Anura
Skeletal Muscle
Tetraethylammonium
Patch-Clamp Techniques
Muscles

ASJC Scopus subject areas

  • Physiology

Cite this

Differential effects of tetracaine on delayed potassium channels and displacement currents in frog skeletal muscle. / Almers, Wolfhard.

In: Journal of Physiology, Vol. 262, No. 3, 1976, p. 613-637.

Research output: Contribution to journalArticle

@article{b9254b04533049709e8cc4f9b584b85a,
title = "Differential effects of tetracaine on delayed potassium channels and displacement currents in frog skeletal muscle",
abstract = "Delayed K+ currents and displacement currents were studied with a voltage clamp technique. In normal fibres, the conductance of the delayed channel grows e fold per 3 millivolts at sufficiently negative potentials and reaches a limiting value of 2-10 m mho/cm2 (mean 5.8 m mho/cm2) at positive potentials. Adding tetracaine (2 mM) reduces the limiting conductance, shifts the voltage dependence of the delayed channel to +25 mV more positive potentials and slows the kinetics fourfold. By contrast, the displacement currents are virtually unaltered by 2 mM tetracaine. Their voltage dependence is shifted by less than 5 mV and their kinetics are unaffected. Tetraethylammonium ions (TEA) are known to slow the kinetics of delayed K+ channels fivefold but fail, like tetracaine, to change the kinetics of the displacement currents. Both tetracaine and TEA have thus large effects on the 'gating' of the delayed channel, yet little or none on the displacement currents. This suggests that the displacement currents in skeletal muscle are for the most part unrelated to the opening and closing of delayed channels. It is estimated that 'gating' the delayed channel in muscle may require no more than 1 or 2{\%} of the observed charge displacement.",
author = "Wolfhard Almers",
year = "1976",
language = "English (US)",
volume = "262",
pages = "613--637",
journal = "Journal of Physiology",
issn = "0022-3751",
publisher = "Wiley-Blackwell",
number = "3",

}

TY - JOUR

T1 - Differential effects of tetracaine on delayed potassium channels and displacement currents in frog skeletal muscle

AU - Almers, Wolfhard

PY - 1976

Y1 - 1976

N2 - Delayed K+ currents and displacement currents were studied with a voltage clamp technique. In normal fibres, the conductance of the delayed channel grows e fold per 3 millivolts at sufficiently negative potentials and reaches a limiting value of 2-10 m mho/cm2 (mean 5.8 m mho/cm2) at positive potentials. Adding tetracaine (2 mM) reduces the limiting conductance, shifts the voltage dependence of the delayed channel to +25 mV more positive potentials and slows the kinetics fourfold. By contrast, the displacement currents are virtually unaltered by 2 mM tetracaine. Their voltage dependence is shifted by less than 5 mV and their kinetics are unaffected. Tetraethylammonium ions (TEA) are known to slow the kinetics of delayed K+ channels fivefold but fail, like tetracaine, to change the kinetics of the displacement currents. Both tetracaine and TEA have thus large effects on the 'gating' of the delayed channel, yet little or none on the displacement currents. This suggests that the displacement currents in skeletal muscle are for the most part unrelated to the opening and closing of delayed channels. It is estimated that 'gating' the delayed channel in muscle may require no more than 1 or 2% of the observed charge displacement.

AB - Delayed K+ currents and displacement currents were studied with a voltage clamp technique. In normal fibres, the conductance of the delayed channel grows e fold per 3 millivolts at sufficiently negative potentials and reaches a limiting value of 2-10 m mho/cm2 (mean 5.8 m mho/cm2) at positive potentials. Adding tetracaine (2 mM) reduces the limiting conductance, shifts the voltage dependence of the delayed channel to +25 mV more positive potentials and slows the kinetics fourfold. By contrast, the displacement currents are virtually unaltered by 2 mM tetracaine. Their voltage dependence is shifted by less than 5 mV and their kinetics are unaffected. Tetraethylammonium ions (TEA) are known to slow the kinetics of delayed K+ channels fivefold but fail, like tetracaine, to change the kinetics of the displacement currents. Both tetracaine and TEA have thus large effects on the 'gating' of the delayed channel, yet little or none on the displacement currents. This suggests that the displacement currents in skeletal muscle are for the most part unrelated to the opening and closing of delayed channels. It is estimated that 'gating' the delayed channel in muscle may require no more than 1 or 2% of the observed charge displacement.

UR - http://www.scopus.com/inward/record.url?scp=0017036083&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0017036083&partnerID=8YFLogxK

M3 - Article

C2 - 1087642

AN - SCOPUS:0017036083

VL - 262

SP - 613

EP - 637

JO - Journal of Physiology

JF - Journal of Physiology

SN - 0022-3751

IS - 3

ER -