Fig. 1.
The glutaminase (GLNase) inhibitor 6-diazo-5-oxo-l-norleucine (DON) and the glutamine synthetase (GS) inhibitor l-methionine sulfoximine (MSO) interfere with uptake of l-[3H]glutamine but not l-[3H]glutamate in primary rat astrocytes. A: comparative kinetics of l-[3H]glutamine and l-[3H]glutamate uptake by cultured astrocytes. Total concentration of both amino acids was adjusted to 2 μM. The results are mean values ± SE of 6 independent determinations. When not shown, SE values were less than symbol. B: effects of 1 mM DON and 1 mM MSO on cumulative astrocytic l-[3H]glutamate uptake measured for 40 min. The results are the mean values ± SE of 6 independent determinations in 2 experiments. C: effects of 1 mM DON and 1 mM MSO on cumulative astrocytic l-[3H]glutamine uptake measured for 40 min. The results are the mean values ± SE of 6 independent determinations in 2 experiments. ***P < 0.001 vs. basal uptake values. D: 1 mM DON triggers efflux of intracellular l-[3H]glutamine. The results are the mean values ± SE of 4 experiments. ***P < 0.001 DON vs. basal release values, repeated measures ANOVA.