FIGURE 2.

Schematic of the experimental system used to measure the permeability of the in vitro BBB models to water and fluorescently-labeled solutes. The Transwell filter with the cell layers was sealed in a chamber. For solute transport, the fluorescently-labeled test solute was added to the upper chamber, transport of test solutes across the cell layer was quantified by an automated fluorometer and the solute permeability was calculated accordingly. For water transport, the reservoir was lowered to create a pressure gradient across the cell layer, the water flux across the cell monolayer was measured by a bubble tracker, and the hydraulic conductivity was determined accordingly.