Metabolism of 15NH3 in organotypic cerebellar explants and cultured astrocytes: studies with gas chromatography-mass spectrometry.

Gas chromatography-mass spectrometry was used to study the metabolism of 15NH3 in organotypic cerebellar explants and cultured astrocyte monolayers. A steady-state level of 15NH3 was present by 1 min in both systems. Steady-state labeling in L-[amide-15N] glutamine, L-[15N]alanine, L-[15N]glutamate, and L-[15N]aspartate was attained by 1 min after 15NH3 addition in the organotypic cerebellar explants and by approximately 5 min in the cultured astrocytes. No measurable 15N labeling was noted in either glycine or serine in either system.