Glucose Transfer across the Blood-Brain Barrier

Abstract

Publisher Summary This chapter describes glucose transfer across the blood-brain barrier. The brain is almost entirely dependent on glucose combustion. Under normal conditions glucose is responsible for 90% of the brain's oxidative metabolism. Glucose transport is saturable and stereospecific, and closely related carbohydrates are competitively transported by the same mechanism. The mechanism is Na+ insensitive, at least on the blood side, and is commonly regarded as equilibrating with symmetrical properties in both directions. In contrast to the effect of insulin on metabolism exerted in the parenchyma it is generally assumed that insulin has no direct influence on blood–brain barrier transport. During insulin infusion, unidirectional flux of glucose across the blood-brain barrier increased significantly without any concomitant change in net uptake of glucose by the brain. Glucose transfer across the blood–brain barrier is not a fixed entity and varies considerably with changing physiological conditions. It is influenced by cerebral blood flow, pH, insulin, and possibly induction phenomena.