Figure 3.

Schematic representation of the diffusion of glutamate from the brain to the blood. Under physiological conditions, the brain–blood barrier (BBB) acts as a semi-permeable membrane preventing the diffusion of glutamate from the blood to the brain. During ischemia, glutamate concentrations in the brain rise to levels 10 times higher than normal, leading to increased blood levels of glutamate as well. Lowering blood glutamate levels leads to a reduction of extracellular levels in the brain.