TY - JOUR
T1 - Surface periarterial spaces of the mouse brain are open, not porous
T2 - Surface periarterial spaces of the mouse brain are open, not porous
AU - Min Rivas, Fatima
AU - Liu, Jia
AU - Martell, Benjamin C.
AU - Du, Ting
AU - Mestre, Humberto
AU - Nedergaard, Maiken
AU - Tithof, Jeffrey
AU - Thomas, John H.
AU - Kelley, Douglas H.
N1 - Publisher Copyright:
© 2020 The Author(s).
PY - 2020/11/1
Y1 - 2020/11/1
N2 - Fluid-dynamic models of the flow of cerebrospinal fluid in the brain have treated the perivascular spaces either as open (without internal solid obstacles) or as porous. Here, we present experimental evidence that pial (surface) periarterial spaces in mice are essentially open. (1) Paths of particles in the perivascular spaces are smooth, as expected for viscous flow in an open vessel, not diffusive, as expected for flow in a porous medium. (2) Time-averaged velocity profiles in periarterial spaces agree closely with theoretical profiles for viscous flow in realistic models, but not with the nearly uniform profiles expected for porous medium. Because these spaces are open, they have much lower hydraulic resistance than if they were porous. To demonstrate, we compute hydraulic resistance for realistic periarterial spaces, both open and porous, and show that the resistance of the porous spaces are greater, typically by a factor of a hundred or more. The open nature of these periarterial spaces allows significantly greater flow rates and more efficient removal of metabolic waste products.
AB - Fluid-dynamic models of the flow of cerebrospinal fluid in the brain have treated the perivascular spaces either as open (without internal solid obstacles) or as porous. Here, we present experimental evidence that pial (surface) periarterial spaces in mice are essentially open. (1) Paths of particles in the perivascular spaces are smooth, as expected for viscous flow in an open vessel, not diffusive, as expected for flow in a porous medium. (2) Time-averaged velocity profiles in periarterial spaces agree closely with theoretical profiles for viscous flow in realistic models, but not with the nearly uniform profiles expected for porous medium. Because these spaces are open, they have much lower hydraulic resistance than if they were porous. To demonstrate, we compute hydraulic resistance for realistic periarterial spaces, both open and porous, and show that the resistance of the porous spaces are greater, typically by a factor of a hundred or more. The open nature of these periarterial spaces allows significantly greater flow rates and more efficient removal of metabolic waste products.
KW - brain clearance system
KW - cerebrospinal fluid
KW - fluid dynamics
KW - glymphatic system
KW - hydraulic network models
KW - perivascular spaces
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U2 - 10.1098/rsif.2020.0593
DO - 10.1098/rsif.2020.0593
M3 - Article
C2 - 33171075
AN - SCOPUS:85095541159
SN - 1742-5689
VL - 17
JO - Journal of the Royal Society Interface
JF - Journal of the Royal Society Interface
IS - 172
M1 - 0593
ER -