Sustained spontaneous activity of ranvier nodes induced by the combined actions of TEA and lack of calcium

Claude Bergmann, Wolfgang Nonner, Robert Stämpfli

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

Superfusion of a Ranvier node of r. esculenta and xenopus l. with Ringer's of reduced Ca++-content (0.05 to 0.1 mM/l) containing 5 mM/l TEA, induced spontaneous activity for more than 30 min. The frequency of discharge at beginning of superfusion was 192±39/sec. It declined within 30 to 60 sec to a steady value of 76±26/sec. Such membranes were submitted to voltage clamp analysis: Depolarisations between V=0 and 20 mV produced initial, between 0 and 10 mV steady state inward currents. This reversal of steady state currents compared to normal membranes is due to enhanced Na+-permeability (lack of Ca++) and to reduced K+-permeability (action of TEA). Analysis of the sodium system revealed (a) shift of the m (V) curve by 10 mV to smaller depolarizations (b) shift of the h (V) curve in same direction by 5 mV (c) little change of time constants τm and τk. The product m2h near the resting potential differs from zero. Spontaneous activity can thus be explained by the following cycle: After repolarization of the spike the nearly abolished sodium permeability grows toward its steady state value (h→h, m≈m). Accordingly the sodium inward current increases with the evolution of h and produces a depolarization (pacemaker potential) which by the early rise of the variable m becomes regenerative and leads to the next spike.

Original languageEnglish
Pages (from-to)24-37
Number of pages14
JournalPflügers Archiv European Journal of Physiology
Volume302
Issue number1
DOIs
StatePublished - Mar 1 1968
Externally publishedYes

Fingerprint

Ranvier's Nodes
Depolarization
Permeability
Sodium
Calcium
Membranes
Pacemakers
Clamping devices
Xenopus
Systems Analysis
Membrane Potentials
Electric potential

Keywords

  • Calcium Lack
  • Ranvier Node
  • Spontaneous Activity
  • TEA
  • Voltage Clamp

ASJC Scopus subject areas

  • Physiology

Cite this

Sustained spontaneous activity of ranvier nodes induced by the combined actions of TEA and lack of calcium. / Bergmann, Claude; Nonner, Wolfgang; Stämpfli, Robert.

In: Pflügers Archiv European Journal of Physiology, Vol. 302, No. 1, 01.03.1968, p. 24-37.

Research output: Contribution to journalArticle

@article{6a7a6d9c0a3c4da895a03169fc3cef97,
title = "Sustained spontaneous activity of ranvier nodes induced by the combined actions of TEA and lack of calcium",
abstract = "Superfusion of a Ranvier node of r. esculenta and xenopus l. with Ringer's of reduced Ca++-content (0.05 to 0.1 mM/l) containing 5 mM/l TEA, induced spontaneous activity for more than 30 min. The frequency of discharge at beginning of superfusion was 192±39/sec. It declined within 30 to 60 sec to a steady value of 76±26/sec. Such membranes were submitted to voltage clamp analysis: Depolarisations between V=0 and 20 mV produced initial, between 0 and 10 mV steady state inward currents. This reversal of steady state currents compared to normal membranes is due to enhanced Na+-permeability (lack of Ca++) and to reduced K+-permeability (action of TEA). Analysis of the sodium system revealed (a) shift of the m∞ (V) curve by 10 mV to smaller depolarizations (b) shift of the h∞ (V) curve in same direction by 5 mV (c) little change of time constants τm and τk. The product m∞2h∞ near the resting potential differs from zero. Spontaneous activity can thus be explained by the following cycle: After repolarization of the spike the nearly abolished sodium permeability grows toward its steady state value (h→h∞, m≈m∞). Accordingly the sodium inward current increases with the evolution of h and produces a depolarization (pacemaker potential) which by the early rise of the variable m becomes regenerative and leads to the next spike.",
keywords = "Calcium Lack, Ranvier Node, Spontaneous Activity, TEA, Voltage Clamp",
author = "Claude Bergmann and Wolfgang Nonner and Robert St{\"a}mpfli",
year = "1968",
month = "3",
day = "1",
doi = "10.1007/BF00586780",
language = "English",
volume = "302",
pages = "24--37",
journal = "Pflugers Archiv European Journal of Physiology",
issn = "0031-6768",
publisher = "Springer Verlag",
number = "1",

}

TY - JOUR

T1 - Sustained spontaneous activity of ranvier nodes induced by the combined actions of TEA and lack of calcium

AU - Bergmann, Claude

AU - Nonner, Wolfgang

AU - Stämpfli, Robert

PY - 1968/3/1

Y1 - 1968/3/1

N2 - Superfusion of a Ranvier node of r. esculenta and xenopus l. with Ringer's of reduced Ca++-content (0.05 to 0.1 mM/l) containing 5 mM/l TEA, induced spontaneous activity for more than 30 min. The frequency of discharge at beginning of superfusion was 192±39/sec. It declined within 30 to 60 sec to a steady value of 76±26/sec. Such membranes were submitted to voltage clamp analysis: Depolarisations between V=0 and 20 mV produced initial, between 0 and 10 mV steady state inward currents. This reversal of steady state currents compared to normal membranes is due to enhanced Na+-permeability (lack of Ca++) and to reduced K+-permeability (action of TEA). Analysis of the sodium system revealed (a) shift of the m∞ (V) curve by 10 mV to smaller depolarizations (b) shift of the h∞ (V) curve in same direction by 5 mV (c) little change of time constants τm and τk. The product m∞2h∞ near the resting potential differs from zero. Spontaneous activity can thus be explained by the following cycle: After repolarization of the spike the nearly abolished sodium permeability grows toward its steady state value (h→h∞, m≈m∞). Accordingly the sodium inward current increases with the evolution of h and produces a depolarization (pacemaker potential) which by the early rise of the variable m becomes regenerative and leads to the next spike.

AB - Superfusion of a Ranvier node of r. esculenta and xenopus l. with Ringer's of reduced Ca++-content (0.05 to 0.1 mM/l) containing 5 mM/l TEA, induced spontaneous activity for more than 30 min. The frequency of discharge at beginning of superfusion was 192±39/sec. It declined within 30 to 60 sec to a steady value of 76±26/sec. Such membranes were submitted to voltage clamp analysis: Depolarisations between V=0 and 20 mV produced initial, between 0 and 10 mV steady state inward currents. This reversal of steady state currents compared to normal membranes is due to enhanced Na+-permeability (lack of Ca++) and to reduced K+-permeability (action of TEA). Analysis of the sodium system revealed (a) shift of the m∞ (V) curve by 10 mV to smaller depolarizations (b) shift of the h∞ (V) curve in same direction by 5 mV (c) little change of time constants τm and τk. The product m∞2h∞ near the resting potential differs from zero. Spontaneous activity can thus be explained by the following cycle: After repolarization of the spike the nearly abolished sodium permeability grows toward its steady state value (h→h∞, m≈m∞). Accordingly the sodium inward current increases with the evolution of h and produces a depolarization (pacemaker potential) which by the early rise of the variable m becomes regenerative and leads to the next spike.

KW - Calcium Lack

KW - Ranvier Node

KW - Spontaneous Activity

KW - TEA

KW - Voltage Clamp

UR - http://www.scopus.com/inward/record.url?scp=0014237067&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0014237067&partnerID=8YFLogxK

U2 - 10.1007/BF00586780

DO - 10.1007/BF00586780

M3 - Article

C2 - 5693805

AN - SCOPUS:0014237067

VL - 302

SP - 24

EP - 37

JO - Pflugers Archiv European Journal of Physiology

JF - Pflugers Archiv European Journal of Physiology

SN - 0031-6768

IS - 1

ER -