Fig. 6. (A) The glucose transporter at the blood–brain barrier, GLUT-1, is upregulated in rat brain in response to hypobaric hypoxia from 6 h (6h) to 21 days (21d), reaching a maximum between 1 and 2 weeks. After return to normoxia over 3 weeks (1R – 21R) there is a return towards control levels of the GLUT-1 protein. (B) Immunohistochemistry of serial sections from rat cerebellar cortex suggesting that VEGF is upregulated in cells that are also positive for the astrocyte specific marker glial fibrillary acific protein (GFAP), rather than the capillary endothelial cells that are positive for the glucose transporter (GLUT-1) (LaManna et al., unpublished observations).