Koch Timo, Mardal Kent-André
Department of Mathematics, University of Oslo, Oslo, Norway.
Department of Scientific Computing and Numerical Analysis (SCAN), Simula Research Laboratory, Oslo, Norway.
Interface Focus. 2025 Apr 4;15(1):20240042. doi: 10.1098/rsfs.2024.0042.
We present a modelling framework for describing bulk fluid flow in brain tissue. Within this framework, using computational simulation, we estimate bulk flow velocities in the grey matter parenchyma due to static or slowly varying water potential gradients-hydrostatic pressure gradients and osmotic pressure gradients. Working with the situation that experimental evidence and some model parameter estimates, as we point out, are presently insufficient to estimate velocities precisely, we explore feasible parameter ranges resulting in a range of estimates. We consider the effect of realistic microvascular architecture (extracted from mouse cortical grey matter). Although the estimated velocities are small in magnitude (e.g. in comparison to blood flow velocities), the passive transport of solutes with the bulk fluid can be a relevant process when considering larger molecules transported over larger distances. We compare velocity magnitudes resulting from filtration and pulsations. Filtration can lead to continuous directed fluid flow in the parenchyma, while pulsation-driven flow is (at least partly) reversible. For the first time, we consider the effect of the vascular architecture on the velocity distribution in a tissue sample of 1 mm cortical grey matter tissue. We conclude that both filtration and pulsations are potentially potent drivers for fluid flow.
我们提出了一个用于描述脑组织中大量流体流动的建模框架。在此框架内，我们通过计算模拟来估计由于静态或缓慢变化的水势梯度（静水压力梯度和渗透压梯度）导致的灰质实质中的大量流动速度。鉴于目前如我们所指出的实验证据和一些模型参数估计不足以精确估计速度，我们探讨了可行的参数范围，从而得出一系列估计值。我们考虑了实际微血管结构（从小鼠皮质灰质中提取）的影响。尽管估计的速度大小较小（例如与血流速度相比），但当考虑较大分子在较大距离上的运输时，溶质与大量流体的被动运输可能是一个相关过程。我们比较了由过滤和脉动产生的速度大小。过滤可导致实质中连续的定向流体流动，而脉动驱动的流动（至少部分）是可逆的。我们首次考虑了血管结构对1毫米皮质灰质组织样本中速度分布的影响。我们得出结论，过滤和脉动都可能是流体流动的潜在强大驱动力。
