Metabolic fate of [U-14C]-labeled glutamate in primary cultures of mouse astrocytes as a function of development.

The metabolic fate of [U-14C]-labeled glutamate in astrocytes grown in primary cultures for 1-3 weeks in the absence or presence of dibutyryl cyclic AMP was followed using dansylation with 3H-dansyl chloride and subsequent thin layer chromatography of the dansylated amino acids. No indication was found of classical metabolic compartmentation, i.e., the specific radioactivity of glutamine (14C/3H ratio) never exceeded that of its precursor, glutamate. In accordance with a relatively late maturation of glutamine synthetase activity the rate of formation of labeled glutamine was much faster in 3-week-old than in 1-week-old cultures. The opposite was found for aspartate formation, but under all conditions incorporation of radioactivity into aspartate was pronounced.