This study characterized the Na⁺-dependent transport of L-glutamine by a human neuroblastoma cell line, SK-N-SH. The Na⁺-dependent component represented >95% of the total glutamine uptake. Kinetic studies showed a single saturable high-affinity carrier with a Michaelis constant (K_m) of 163 ± 23 µM and a maximum transport velocity (V_max) of 13,713 ± 803 pmol · mg protein¹ · min¹. Glutamine uptake was markedly inhibited in the presence of L-alanine, L-asparagine, and L-serine. Li⁺ did not substitute for Na⁺. These data show that L-glutamine is predominantly taken up through system ASC. Glutamine deprivation resulted in the decrease of glutamine transport by a mechanism that decreased V_max without affecting K_m. The expression of the system ASC subtype ASCT2 decreased in the glutamine-deprived group, whereas glutamine deprivation did not induce changes in system ASC subtype ASCT1 mRNA expression. Adaptive increases in Na⁺-dependent glutamate, Na⁺-dependent 2-(methylamino)isobutyric acid, and Na⁺-independent leucine transport were observed under glutamine-deprived conditions, which were completely blocked by actinomycin D and cycloheximide. These mechanisms may allow cells to survive and even grow under nutrient-deprived conditions.