Smith Q R, Woodbury D M, Johanson C E
Brain Res. 1982 Feb;255(2):181-98. doi: 10.1016/0165-3806(82)90019-0.
The kinetics of penetration of radioactive [36Cl]-, [22Na]- and [3H]mannitol into the choroid plexus-CSF brain system was investigated in 1-week, 2-week and adult Sprague-Dawley rats. For adult rats (5 weeks), 36Cl and 22Na uptake by the choroid plexus of lateral ventricle (LVCP) and fourth ventricle (4VCP) resolved into a fast component (t1/2 0.02 - 0.05 h) representing isotope distribution within the extracellular and residual erythrocyte compartments, and a slow component (t1/2 0.8 - 1.9 h) representing isotope movement into the epithelial cell compartment. From steady-state distribution data, choroid cell [Cl] in both LVCP and 4VCP was calculated to be 67 mmol/kg cell H2O, a level nearly 4 times greater than that predicted by the membrane potential for passive distribution. In 1-week immature rats cell [Cl] and [Na] in the choroid plexuses were even greater than the corresponding levels in adults, probably because ion transport across the basolateral membrane is not yet coupled with ion movement from cell to CSF. In mature rats the 36Cl and 22Na uptake into the CSF resolved into 2 components (t1/2 0.18 h, fractional volume 0.24 and t1/2 1.2 h, fractional volume 0.76); however, the fast component of CSF uptake, which likely represents isotope movement across the choroid plexuses, was negligible in the 1-week animals. Permeability-surface area products (PA) were determined for the blood-CSF barrier (i.e. the choroid plexuses) as well as the blood-brain barrier (cerebral cortex and cerebellum). The PA values for 36Cl and 22Na as determined by the fast component of CSF uptake (choroid plexus secretion?) were an order of magnitude less in the 1-week rats than in adults. In contrast, the effective permeability of the blood-CSF barrier as well as the blood-brain barrier, as evaluated by changes in PA of [3H]mannitol, decreased steadily with advancing age.
在1周龄、2周龄和成年Sprague-Dawley大鼠中研究了放射性[36Cl] -、[22Na] -和[3H]甘露醇进入脉络丛-脑脊液脑系统的动力学。对于成年大鼠（5周龄），侧脑室脉络丛（LVCP）和第四脑室脉络丛（4VCP）对36Cl和22Na的摄取可分解为一个快速成分（t1/2为0.02 - 0.05小时），代表细胞外和残余红细胞隔室内的同位素分布，以及一个缓慢成分（t1/2为0.8 - 1.9小时），代表同位素进入上皮细胞隔室的移动。根据稳态分布数据，计算出LVCP和4VCP中脉络丛细胞的[Cl]为67 mmol/kg细胞H2O，该水平比被动分布的膜电位预测值高近4倍。在1周龄的未成熟大鼠中，脉络丛中的细胞[Cl]和[Na]甚至高于成年大鼠的相应水平，这可能是因为跨基底外侧膜的离子转运尚未与离子从细胞到脑脊液的移动耦合。在成年大鼠中，36Cl和22Na进入脑脊液的过程可分解为两个成分（t1/2为0.18小时，分数体积为0.24；t1/2为1.2小时，分数体积为0.76）；然而，在1周龄的动物中，脑脊液摄取的快速成分（可能代表同位素穿过脉络丛的移动）可以忽略不计。测定了血-脑脊液屏障（即脉络丛）以及血-脑屏障（大脑皮层和小脑）的通透表面积乘积（PA）。通过脑脊液摄取的快速成分（脉络丛分泌？）测定的36Cl和22Na的PA值在1周龄大鼠中比成年大鼠低一个数量级。相反，通过[3H]甘露醇PA的变化评估，血-脑脊液屏障以及血-脑屏障的有效通透性随着年龄的增长而稳步下降。
