Glial cells influence polarity of the blood-brain barrier.

Polarity has been shown to exist at the blood-brain barrier (BBB) with respect to Na+-dependent neutral amino acid transport. A situation similar to the endothelial-astrocyte relationship existing at the BBB can be produced by growing cultured cerebral endothelium on one side of a filter and C6 glial cells on the other in an enclosed double chamber. In this setting 3H-alpha-methylaminoisobutyric acid transport can be demonstrated and is more rapid from the glial surface across the endothelium, as compared with transport in the opposite direction. The observation supports a glial influence on BBB polarity in this system.