Figure 2.
Axon schematic showing the distribution of glucose transporters (GLUT), and monocarboxylate transporters (MCT) in the axon, astrocytes and oligodendrocytes. GLUTs move glucose into the cell, while MCTs transport monocarboxylates such as lactate, pyruvate, and β-hydroxybutyrate. Glia express MCT1 and MCT4, while axons express MCT2. The kinetics of the MCTs are such that MCT1 is best suited for lactate export and MCT2 for lactate uptake because of its higher affinity for lactate (see text). The node of Ranvier is concentrated with ion channels (not shown) necessary for saltatory conduction. Astrocytes can interface with the axon at the node of Ranvier. Oligodendrocytes myelinate the axon; the region between nodes of Ranvier is the internode.