FIG. 2.

A human BBB capillary immunostained for the full-length GLUT1 glucose transporter (identified by 10-nm gold particles), and GFAP (GFAP, linked to 20-nm gold particles, using antisera and methods described elsewhere.² Note the high GLUT1-expressing type A endothelial cell on the right side of the capillary can be sharply contrasted with the low GLUT1-expressing type B cell (open arrows) on the upper left. In the type A cell, luminal membrane expression is greater than that of the abluminal membrane, and erythrocyte membrane GLUT1 expression is intermediate between that of the type A versus the type B endothelial cell. GFAP epitopes (upper right) are uniformly distributed throughout the astrocyte.