FIGURE 3.

bEnd3 monolayer permeability is modulated by basolateral culturing conditions. bEnd3 cells were grown to confluence, and the media in the basolateral chamber was changed to either 10% FBS containing media, serum-free media, or a 50:50 mixture of serum-free media and astrocyte-conditioned media. After 1–7 days exposure to different media conditions, paracellular permeability of [¹⁴C]sucrose was measured. Permeability of the monolayers decreased over time in all treatment groups. For the first three days of exposure, there was a significant loosening of the monolayers exposed to astrocyte-conditioned media as compared to control (*) or serum-free media (^). By day 4, the monolayers exposed to serum-free media were significantly tighter then those exposed to 10% FBS or astrocyte-conditioned media. By day 7, there was no significant difference between 10% FBS and serum-free media exposed monolayers, while the monolayers exposed to astrocyte-conditioned media were again more permeable then the other two groups. n=8–16 filters, * p<0.05 versus 10% FBS, ** p<0.01 versus 10% FBS, *** p<0.001 versus 10% FBS, ^ p<0.05 versus serum-free media, ^^^ p<0.001 versus serum-free media.