A Disequilibrium Oncotic Model of Brain Fluid Flux, 2026, Edwards

[forestglip]

A Disequilibrium Oncotic Model of Brain Fluid Flux

Edwards, Jonathan

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Abstract
Application of the revised Starling model proposed by Levick and Michel (2010) suggests that cerebrospinal fluid (CSF) production is essential for maintenance of a low interstitial protein content in brain irrespective of any role in waste clearance.

The anatomy of the brain, ventricles and choroid suggests that CSF enters brain by net bulk diffusion through both internal ependymal and external pial surfaces as part of a continual refreshment of low protein intertitium in the manner of a repeatedly squeezed sponge or mop, under forces such as arterial pulsation.

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[Jonathan Edwards]

Thanks for putting that up. There is actually an edited version now,, which will go up tomorrow:

 

[Jonathan Edwards]

I have had a discussion with Nanna MacAulay about the model. She agrees that CSF flux is still not settled and that the glymphatic model has significant problems. But I think she is working with the sort of modelling maths that Rodney Levick and I had to overcome when we started thinking about joint fluid.

People talk in terms of semipermeable membranes but materials like brain tissue behave very differently from stirred tea because they consist of a complex mix of solid and fluid phase elements. When you get to cartilage all the rules are turned on their heads because it is the ultimate mixture of solid and fluid elements fighting each other.

I may still be getting this wrong but I think there are major mis-steps in the received wisdom arguments about parenchymal vessel water flux and other things.