Determination of Brain Interstitial Concentrations by Microdialysis

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Determination of Brain Interstitial Concentrations by Microdialysis. / Benveniste, Helene; Hansen, Anker Jon; Ottosen, Niels Saabye.

I: Journal of Neurochemistry, Vol. 52, Nr. 6, 1989, s. 1741-1750.

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Benveniste, Helene ; Hansen, Anker Jon ; Ottosen, Niels Saabye. / Determination of Brain Interstitial Concentrations by Microdialysis. I: Journal of Neurochemistry. 1989 ; Vol. 52, Nr. 6. s. 1741-1750.

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TY - JOUR

T1 - Determination of Brain Interstitial Concentrations by Microdialysis

AU - Benveniste, Helene

AU - Hansen, Anker Jon

AU - Ottosen, Niels Saabye

PY - 1989

Y1 - 1989

N2 - Microdialysis is an extensively used technique for the study of solutes in brain interstitial space. The method is based on collection of substances by diffusion across a dialysis membrane positioned in the brain. The outflow concentration reflects the interstitial concentration of the substance of interest, but the relationship between these two entities is at present unclear. So far, most evaluations have been based solely on calibrations in saline. This procedure is misleading, because the ease by which molecules in saline diffuse into the probe is different from that of tissue. We describe here a mathematical analysis of mass transport into the dialysis probe in tissue based on diffusion equations in complex media. The main finding is that diffusion characteristics of a given substance have to be included in the formula. These include the tortuosity factor (λ) and the extracellular volume fraction (α). We have substantiated this by studies in a welldefined complex medium (red blood cell suspensions) as well as in brain. We conclude that the traditional calculation procedure results in interstitial concentrations that are too low by a factor of λ2/α for a given compound.

AB - Microdialysis is an extensively used technique for the study of solutes in brain interstitial space. The method is based on collection of substances by diffusion across a dialysis membrane positioned in the brain. The outflow concentration reflects the interstitial concentration of the substance of interest, but the relationship between these two entities is at present unclear. So far, most evaluations have been based solely on calibrations in saline. This procedure is misleading, because the ease by which molecules in saline diffuse into the probe is different from that of tissue. We describe here a mathematical analysis of mass transport into the dialysis probe in tissue based on diffusion equations in complex media. The main finding is that diffusion characteristics of a given substance have to be included in the formula. These include the tortuosity factor (λ) and the extracellular volume fraction (α). We have substantiated this by studies in a welldefined complex medium (red blood cell suspensions) as well as in brain. We conclude that the traditional calculation procedure results in interstitial concentrations that are too low by a factor of λ2/α for a given compound.

KW - Interstitial space size

KW - Tortuosity factor

KW - Diffusion characteristics

KW - Mass transport

KW - Complex media

KW - Diffusion equations

KW - Brain interstitial space

KW - Microdialysis

U2 - 10.1111/j.1471-4159.1989.tb07252.x

DO - 10.1111/j.1471-4159.1989.tb07252.x

M3 - Article

VL - 52

SP - 1741

EP - 1750

JO - Journal of Neurochemistry

JF - Journal of Neurochemistry

SN - 1471-4159

IS - 6

ER -