scholarly journals THE EFFECT OF NITRATE AND THIOCYANATE IONS ON THE RESTING AND ACTION POTENTIALS OF COBALT-TREATED SINGLE NODE OF RANVIER

1963 ◽  
Vol 13 (3) ◽  
pp. 219-230 ◽  
Author(s):  
Saburo HASHIMURA ◽  
Takuro OSA
Keyword(s):  
Action Potentials ◽  
Node Of Ranvier ◽  
Single Node

Action potentials and membrane currents in the human node of Ranvier

1995 ◽  
Vol 430 (2) ◽  
pp. 283-292 ◽  
Author(s):  
J�rgen R. Schwarz ◽  
Gordon Reid ◽  
Hugh Bostock
Keyword(s):  
Action Potentials ◽  
Node Of Ranvier ◽  
Membrane Currents

scholarly journals Action Potential Propagation and Synchronisation in Myelinated Axons

2019 ◽  
Author(s):  
Helmut Schmidt ◽  
Thomas R. Knösche
Keyword(s):  
White Matter ◽  
Action Potential ◽  
Myelin Sheath ◽  
Action Potentials ◽  
Structural Parameters ◽  
Node Of Ranvier ◽  
Model Parameters ◽  
Mathematical Framework ◽  
Whole Brain ◽  
Action Potential Propagation

AbstractWith the advent of advanced MRI techniques it has become possible to study axonal white matter non-invasively and in great detail. Measuring the various parameters of the long-range connections of the brain opens up the possibility to build and refine detailed models of large-scale neuronal activity. One particular challenge is to find a mathematical description of action potential propagation that is sufficiently simple, yet still biologically plausible to model signal transmission across entire axonal fibre bundles. We develop a mathematical framework in which we replace the Hodgkin-Huxley dynamics by a spike-diffuse-spike model with passive sub-threshold dynamics and explicit, threshold-activated ion channel currents. This allows us to study in detail the influence of the various model parameters on the action potential velocity and on the entrainment of action potentials between ephaptically coupled fibres without having to recur to numerical simulations. Specifically, we recover known results regarding the influence of axon diameter, node of Ranvier length and internode length on the velocity of action potentials. Additionally, we find that the velocity depends more strongly on the thickness of the myelin sheath than was suggested by previous theoretical studies. We further explain the slowing down and synchronisation of action potentials in ephaptically coupled fibres by their dynamic interaction. In summary, this study presents a solution to incorporate detailed axonal parameters into a whole-brain modelling framework.Author summaryWith more and more data becoming available on white-matter tracts, the need arises to develop modelling frameworks that incorporate these data at the whole-brain level. This requires the development of efficient mathematical schemes to study parameter dependencies that can then be matched with data, in particular the speed of action potentials that cause delays between brain regions. Here, we develop a method that describes the formation of action potentials by threshold activated currents, often referred to as spike-diffuse-spike modelling. A particular focus of our study is the dependence of the speed of action potentials on structural parameters. We find that the diameter of axons and the thickness of the myelin sheath have a strong influence on the speed, whereas the length of myelinated segments and node of Ranvier length have a lesser effect. In addition to examining single axons, we demonstrate that action potentials between nearby axons can synchronise and slow down their propagation speed.

scholarly journals The mechanosensitive ion channel TRAAK is localized to the mammalian node of Ranvier

2019 ◽  
Author(s):  
Stephen G. Brohawn ◽  
Weiwei Wang ◽  
Jürgen R. Schwarz ◽  
Annie Handler ◽  
Ernest B. Campbell ◽  
...  
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Polyclonal Antibodies ◽  
Node Of Ranvier ◽  
Nerve Fibers ◽  
Resting Membrane Potential ◽  
Myelinated Nerve ◽  
Myelinated Nerve Fibers ◽  
Behavioral Studies ◽  
Mechanosensitive Ion Channel

ABSTRACTTRAAK is a membrane tension-activated K+ channel that has been associated through behavioral studies to mechanical nociception. We used specific monoclonal antibodies in mice to show that TRAAK is localized exclusively to nodes of Ranvier, the action potential propagating elements of myelinated nerve fibers. Approximately 80 percent of myelinated nerve fibers throughout the central and peripheral nervous system contain TRAAK in an all-nodes or no-nodes per axon fashion. TRAAK is not observed at the axon initial segment where action potentials are first generated. We used polyclonal antibodies, the TRAAK inhibitor RU2 and node clamp amplifiers to demonstrate the presence and functional properties of TRAAK in rat nerve fibers. TRAAK contributes to the ‘leak’ K+ current in mammalian nerve fiber conduction by hyperpolarizing the resting membrane potential, thereby increasing Na+ channel availability for action potential propagation. Mechanical gating in TRAAK might serve a neuroprotective role by counteracting mechanically-induced ectopic action potentials. Alternatively, TRAAK may open in response to mechanical forces in the nodal membrane associated with depolarization during saltatory conduction and thereby contribute to repolarization of the node for subsequent spikes.

scholarly journals ON THE LOCAL RESPONSE OF A SINGLE NODE OF RANVIER UNDER VARIOUS CONDITIONS

1960 ◽  
Vol 10 (3) ◽  
pp. 235-245 ◽  
Author(s):  
MASAMICHI ICHIOKA ◽  
YOKO UEHARA ◽  
SEIKICHI KITAMURA
Keyword(s):  
Node Of Ranvier ◽  
Local Response ◽  
Single Node

scholarly journals A NMR Study of Sodium/Potassium Pumping System in the Node of Ranvier Myelin-Sheath

2021 ◽  
Vol 11 (6) ◽  
pp. 14260-14277
Keyword(s):  
Action Potentials ◽  
Node Of Ranvier ◽  
Physiological Data ◽  
Sodium Potassium ◽  
Voltage Gated ◽  
Pumping System ◽  
Nmr Study ◽  
Helical Coils ◽  
Membrane Bound ◽  
Sodium And Potassium

The QM/MM calculation has been applied to generalize the node of Ranvier results for computing action potentials and electrochemical behavior of membranes that agree with clusters of voltage-gated ion sodium and potassium channels. Ranvier complexes' node is an accurate organization of membrane-bound aqueous boxes. The model applied here shows an electrophysiological phenomenon with simulated structural and physiological data. The quantum effects of various thicknesses in a selected membrane of Galc /DMPC and Galc/NPGS have also been specifically investigated. This allows introducing a capacitive susceptibility that can resonate with the self-induction of helical coils or ion channels, the resonance of which is the main reason for various biological pulses.

Three-Dimensional Reconstruction of a Node of Ranvier Obtained by Serial Section Electron Tomography

2000 ◽  
Vol 6 (S2) ◽  
pp. 866-867
Author(s):  
G. Sosinsky ◽  
T. Deerinck ◽  
R. Greco ◽  
M. Ellisman
Keyword(s):  
Action Potentials ◽  
Electron Tomography ◽  
Three Dimensional ◽  
Node Of Ranvier ◽  
Na Channel ◽  
Nodes Of Ranvier ◽  
Myelinated Axons ◽  
Axonal Diameter ◽  
Dimensional Reconstruction ◽  
Section Electron

Nodes of Ranvier are sites on myelinated axons where the insulating layers of myelin are interrupted. They represent an excellent example of a complex cellular structure that contains highly differentiated sub-regions. At these sites of cell-cell specialization, ion fluxes occur which are required for propagation of action potentials. Myelinated axons and their nodes of Ranvier represent an important evolutionary advance for vertebrates that permit very rapid propagation of action potentials without large increases in axonal diameter. This physiological achievement is based on adaptations at a molecular level resulting in an elegant cooperation between glial cells and the axons of neurons.The organization and sub-specialization of the molecular components of the node of Ranvier are complex but often inter-related. The nodal region of axons are enriched in several channel and pump proteins including the voltage-gated Na+ channel, Na+-K+ ATPase and a number of different K+ channel isotypes.

Sign in / Sign up

Export Citation Format

Share Document