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Astrocytes in Control of the Biophysical Properties of Extracellular Space

  • Lydia Vargova
  • Eva Sykova
Chapter

9.1 Extracellular Space (ECS) and Extrasynaptic Transmission

The extracellular space of the central nervous system (CNS) represents the microenvironment of the cellular elements: neurons and glia. Its composition, chemical and biophysical properties are crucial for the proper functioning of neurons and signal transmission. The first estimates of ECS volume that appeared in the second half of the last century were based on electron microscopy. However, the true values were altered by conventional preparation procedures, leading to the erroneous conclusion that the ECS represents less than 5% of the total brain tissue volume (Villegas and Fernandez, 1966). Later, it was shown by a number of different techniques (electron microscopy that preserves the ECS, radiotracers and ion diffusion methods) that under physiological conditions the average ECS volume is about 15–25% of the total adult brain volume [for review see (Nicholson and Sykova, 1998)]. Not only the volume, but also the...

Keywords

Experimental Autoimmune Encephalomyelitis Diffusion Barrier Regulatory Volume Decrease Extracellular Matrix Molecule Astrocytic Process 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Abbreviations

α

Extracellular volume fraction

ADC

Apparent diffusion coefficient

ADCw

Apparent diffusion coefficient of water

AMPA

α-Amino-3-hydroxy-5-metyl-isoxazol-4-propionic acid

CNS

Central nervous system

CSPG

Chondroitin-sulphate proteoglycan

D

Diffusion coefficient

dpw

Day post wounding

DW-MRI

Diffusion-weighted magnetic resonance imaging

EAE

Experimental autoimmune encephalomyelitis

ECM

Extracellular matrix

ECS

Extracellular space

GABA

γ-Aminobutyric acid

GFAP

Glial fibrillary acidic protein

IOS

Intrinsic optical signals

ISM

Ion-selective microelectrode

k'

Nonspecific cellular uptake

[K+]e

Extracellular concentration of potassium ions

λ

Tortuosity

NMDA

N-methyl-d-aspartate

pHe

Extracellular pH

pHi

Intracellular pH

RVD

Regulatory volume decrease

TEA

Tetraethylammonium

TMA

Tetramethylammonium

TN

Tenascin

WHO

World Health Organization

Notes

Acknowledgments

The authors acknowledge the support of grants AV0Z50390512 from the Academy of Sciences of the Czech Republic and LC554 from the Ministry of Education, Youth and Sports of the Czech Republic.

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Authors and Affiliations

  • Lydia Vargova
  • Eva Sykova

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