Vitamin C enters cells via Na+-coupled transporters called SVCT1 and SVCT2. Cellular efflux of vitamin C is mediated by as yet undescribed mechanisms. The oxidized form of vitamin C (dehydroascorbate, DHA) may exit cells via members of the glucose transporter (GLUT) family. In the CNS, astrocytes, the 'supporting cells' of the nervous system, regenerate vitamin C by reduction of DHA. Vitamin C is then transported back into neurons7, 8. The cellular efflux pathways of vitamin C are still poorly understood. Sodium-coupled vitamin C transport has also been observed in cultures of capillary-derived endothelial cells13, but whether this is mediated by SVCT2 and whether it contributes significantly to overall vitamin C transport into the cerebrospinal fluid are still unknown.