Functional hyperemia drives fluid exchange in the paravascular space
Functional hyperemia drives fluid exchange in the paravascular space
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DOI：
10.1186/s12987-020-00214-3
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发表时间：
2020-08-20
影响因子：
7.3
通讯作者：
Costanzo, Francesco
中科院分区：
文献类型：
--
作者：
Kedarasetti, Ravi Teja;Turner, Kevin L.;Costanzo, Francesco
大脑缺乏传统的淋巴系统来清除代谢废物。已经提出通过小动脉血管旁间隙(PVS)的定向液体运动促进代谢物清除。我们进行了模拟，以检验微动脉搏动和扩张是否可以驱动PVS中的脑脊液定向流动，发现小动脉壁运动不能驱动脑脊液定向流动。我们提出了另一种从PVS清除代谢物的方法，即PVS和蛛网膜下腔(SAS)之间的液体交换。在对顺应性脑组织的模拟中，微动脉的搏动并没有驱动PVS和SAS之间明显的液体交换。然而，当小动脉扩张时，如功能性充血时所见，有明显的液体交换。模拟表明，功能性充血可能有助于增加PVS的代谢物清除量。我们用双光子显微镜同时测量了清醒的头部固定小鼠的血管和脑组织移位。这些测量结果表明，大脑会随着PVS中压力的变化而变形，这与我们的模拟一致。我们的结果表明，在研究液体流动和代谢物运输时，需要考虑脑组织的变形性。
The brain lacks a conventional lymphatic system to remove metabolic waste. It has been proposed that directional fluid movement through the arteriolar paravascular space (PVS) promotes metabolite clearance. We performed simulations to examine if arteriolar pulsations and dilations can drive directional CSF flow in the PVS and found that arteriolar wall movements do not drive directional CSF flow. We propose an alternative method of metabolite clearance from the PVS, namely fluid exchange between the PVS and the subarachnoid space (SAS). In simulations with compliant brain tissue, arteriolar pulsations did not drive appreciable fluid exchange between the PVS and the SAS. However, when the arteriole dilated, as seen during functional hyperemia, there was a marked exchange of fluid. Simulations suggest that functional hyperemia may serve to increase metabolite clearance from the PVS. We measured blood vessels and brain tissue displacement simultaneously in awake, head-fixed mice using two-photon microscopy. These measurements showed that brain deforms in response to pressure changes in PVS, consistent with our simulations. Our results show that the deformability of the brain tissue needs to be accounted for when studying fluid flow and metabolite transport.