Perturbation of the metabolism of the brain has serious negative effects on the well-being and survival of the organism. The contribution of the various cell types in the brain to overall metabolism cannot be deter- mined by in vivo experiments. Growth of these sub-populations separately in tissue culture permits examination of their metabolism independently. Furthermore, the effect of varying the extracellular concentration of glucose to mimic conditions seen in vivo in pathologic conditions can be assessed on the separate cell populations. Results from such studies demonstrate that neurons and astroglia handle 2-[14C]DG in a similar fashion under normoglycemic (1.0 - 2.0 mM glucose), slightly hyperglyce- mic (5.0 mM glucose) and hypoglycemic (0.1 - 0.5 mM glucose) conditions; the intracellular:extracellular distribution of 2-[14C]DG is similar in both cell types. Results from studies on glucose were the same as that for 2-[14C]DG at normoglycemic and hyperglycemic levels of glucose. However, results with glucose in the hypoglycemic range were impossible to interpret due to the presence of an intracellular pool of glucose apparently separate from the metabolically active pool. Since the 2- [14C]DG appears to be in equilibrium with the metabolically active glucose pool , movement of glucose at the hypoglycemic levels will have to be inferred from the 2-[14C]DG data. Thus, the ability of neurons and astroglia to transport glucose into the cell's metabolically active pool does not appear to differ.
