Recovery potential in glucose deprived astrocytes

D-glucose deprivation for a 45 min period reduces the ATP and creatine phosphate concentrations of astrocytes. Recovery experiments were initiated by reincubating the cells with D-glucose and glucose replacement metabolites. No recovery of ATP concentration could be obtained even after 1 h of reincubation with the replacement metabolites. After a 45 min incubation period without D-glucose, 14CO2 production fell to 36% and 21% of controls when the cells were reincubated respectively with D-[U-14C]-glucose and L-[2-14C]-pyruvate as substrate marker. When reincubated for 1 h in the presence of L-malate (1 mM)+L-pyruvate (10 mM) with L-[2-14C]-pyruvate as marker, a total recovery of 14CO2 production was ascertained. Reincubation of the glucose deprived cells in the presence of D-glucose (10 mM) did not increase the 14CO2 production indicating that the cells were unable to use D-glucose for oxidative purposes. As pyruvate concentration was dramatically decreased in glucose deprived cells, astrocytes were treated with alpha-ketovalerate (25 mM) which led to an 8-fold increase in pyruvate concentration. In these conditions 14CO2 production did not increase when the cells were incubated in the presence of L-malate (1 mM). O2 consumption of State 4 in astrocytes, submitted to glucose deprivation, decreased. These cells treated with FCCP could not be uncoupled and when reincubated in the presence of replacement metabolites only a 20% increase of oxygen consumption took place.