Cargando…

Electrodiffusive Model for Astrocytic and Neuronal Ion Concentration Dynamics

The cable equation is a proper framework for modeling electrical neural signalling that takes place at a timescale at which the ionic concentrations vary little. However, in neural tissue there are also key dynamic processes that occur at longer timescales. For example, endured periods of intense ne...

Descripción completa

Detalles Bibliográficos
Autores principales: Halnes, Geir, Østby, Ivar, Pettersen, Klas H., Omholt, Stig W., Einevoll, Gaute T.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2013
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3868551/
https://www.ncbi.nlm.nih.gov/pubmed/24367247
http://dx.doi.org/10.1371/journal.pcbi.1003386
_version_ 1782296468611137536
author Halnes, Geir
Østby, Ivar
Pettersen, Klas H.
Omholt, Stig W.
Einevoll, Gaute T.
author_facet Halnes, Geir
Østby, Ivar
Pettersen, Klas H.
Omholt, Stig W.
Einevoll, Gaute T.
author_sort Halnes, Geir
collection PubMed
description The cable equation is a proper framework for modeling electrical neural signalling that takes place at a timescale at which the ionic concentrations vary little. However, in neural tissue there are also key dynamic processes that occur at longer timescales. For example, endured periods of intense neural signaling may cause the local extracellular K(+)-concentration to increase by several millimolars. The clearance of this excess K(+) depends partly on diffusion in the extracellular space, partly on local uptake by astrocytes, and partly on intracellular transport (spatial buffering) within astrocytes. These processes, that take place at the time scale of seconds, demand a mathematical description able to account for the spatiotemporal variations in ion concentrations as well as the subsequent effects of these variations on the membrane potential. Here, we present a general electrodiffusive formalism for modeling of ion concentration dynamics in a one-dimensional geometry, including both the intra- and extracellular domains. Based on the Nernst-Planck equations, this formalism ensures that the membrane potential and ion concentrations are in consistency, it ensures global particle/charge conservation and it accounts for diffusion and concentration dependent variations in resistivity. We apply the formalism to a model of astrocytes exchanging ions with the extracellular space. The simulations show that K(+)-removal from high-concentration regions is driven by a local depolarization of the astrocyte membrane, which concertedly (i) increases the local astrocytic uptake of K(+), (ii) suppresses extracellular transport of K(+), (iii) increases axial transport of K(+) within astrocytes, and (iv) facilitates astrocytic relase of K(+) in regions where the extracellular concentration is low. Together, these mechanisms seem to provide a robust regulatory scheme for shielding the extracellular space from excess K(+).
format Online
Article
Text
id pubmed-3868551
institution National Center for Biotechnology Information
language English
publishDate 2013
publisher Public Library of Science
record_format MEDLINE/PubMed
spelling pubmed-38685512013-12-23 Electrodiffusive Model for Astrocytic and Neuronal Ion Concentration Dynamics Halnes, Geir Østby, Ivar Pettersen, Klas H. Omholt, Stig W. Einevoll, Gaute T. PLoS Comput Biol Research Article The cable equation is a proper framework for modeling electrical neural signalling that takes place at a timescale at which the ionic concentrations vary little. However, in neural tissue there are also key dynamic processes that occur at longer timescales. For example, endured periods of intense neural signaling may cause the local extracellular K(+)-concentration to increase by several millimolars. The clearance of this excess K(+) depends partly on diffusion in the extracellular space, partly on local uptake by astrocytes, and partly on intracellular transport (spatial buffering) within astrocytes. These processes, that take place at the time scale of seconds, demand a mathematical description able to account for the spatiotemporal variations in ion concentrations as well as the subsequent effects of these variations on the membrane potential. Here, we present a general electrodiffusive formalism for modeling of ion concentration dynamics in a one-dimensional geometry, including both the intra- and extracellular domains. Based on the Nernst-Planck equations, this formalism ensures that the membrane potential and ion concentrations are in consistency, it ensures global particle/charge conservation and it accounts for diffusion and concentration dependent variations in resistivity. We apply the formalism to a model of astrocytes exchanging ions with the extracellular space. The simulations show that K(+)-removal from high-concentration regions is driven by a local depolarization of the astrocyte membrane, which concertedly (i) increases the local astrocytic uptake of K(+), (ii) suppresses extracellular transport of K(+), (iii) increases axial transport of K(+) within astrocytes, and (iv) facilitates astrocytic relase of K(+) in regions where the extracellular concentration is low. Together, these mechanisms seem to provide a robust regulatory scheme for shielding the extracellular space from excess K(+). Public Library of Science 2013-12-19 /pmc/articles/PMC3868551/ /pubmed/24367247 http://dx.doi.org/10.1371/journal.pcbi.1003386 Text en © 2013 Halnes et al http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Halnes, Geir
Østby, Ivar
Pettersen, Klas H.
Omholt, Stig W.
Einevoll, Gaute T.
Electrodiffusive Model for Astrocytic and Neuronal Ion Concentration Dynamics
title Electrodiffusive Model for Astrocytic and Neuronal Ion Concentration Dynamics
title_full Electrodiffusive Model for Astrocytic and Neuronal Ion Concentration Dynamics
title_fullStr Electrodiffusive Model for Astrocytic and Neuronal Ion Concentration Dynamics
title_full_unstemmed Electrodiffusive Model for Astrocytic and Neuronal Ion Concentration Dynamics
title_short Electrodiffusive Model for Astrocytic and Neuronal Ion Concentration Dynamics
title_sort electrodiffusive model for astrocytic and neuronal ion concentration dynamics
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3868551/
https://www.ncbi.nlm.nih.gov/pubmed/24367247
http://dx.doi.org/10.1371/journal.pcbi.1003386
work_keys_str_mv AT halnesgeir electrodiffusivemodelforastrocyticandneuronalionconcentrationdynamics
AT østbyivar electrodiffusivemodelforastrocyticandneuronalionconcentrationdynamics
AT pettersenklash electrodiffusivemodelforastrocyticandneuronalionconcentrationdynamics
AT omholtstigw electrodiffusivemodelforastrocyticandneuronalionconcentrationdynamics
AT einevollgautet electrodiffusivemodelforastrocyticandneuronalionconcentrationdynamics