Metabolic interactions of glucose, lactate, and beta-hydroxybutyrate in rat brain slices.

IDE, TAKEHIKO,JURGEN STEINKE, AND GEORGE F. CAHILL, JR. Metabolic interactions of glucose, lactate, and /I-hydroxybutyrate in rat brain slices. Am. J. Physiol. 217(3) : 784-792. 1969.-The metabolism of glucose, lactate, and P-hydroxybutyrate was studied in rat brain slices by following the incorporation of 14C into COz, total lipids, fatty acids, and glycogen singly or in the presence of other unlabeled substrate. Glucose-14C incorporation into COZ, lipids, and glycogen was proportional to glucose concentration in the incubation medium; however, the concentration needed for saturation of these three pathways differed. The activity of the direct oxidative shunt was negligible. Lactate and P-hydroxybutyrate carbon were both incorporated into total lipid and fatty acid proportional to their concentration. In contrast to glucose, neither lactate nor fl-hydroxybutyrate carbon was incorporated into glycogen. However, the addition of glucose to the medium induced a significant incorporation of lactate carbon into glycogen. Addition of lactate or @-hydroxybutyrate inhibited the incorporation of glucose carbon into CO 2, total lipid, and fatty acid, but stimulated its incorporation into glycogen. Both glucose and lactate markedly enhanced the metabolism of P-hydroxybutyrate to CO2 and lipid, suggesting a permissive action of glucose on P-hydroxybutyrate utilization.