Metabolism of [U-(13)C]aspartate by astroglial cultures: nuclear magnetic resonance analysis of the culture media.
In brain the amino acid L-aspartate serves roles as: (1) putative transmitter, (2) protein precursor, (3) donor of atoms for the biosynthesis of pyrimidine and purine bases, and (4) fuel for energy metabolism. Astrocytes dominate aspartate clearance in brain, and in culture they take up aspartate and quickly metabolize it. In brain, only astrocytes were shown to express the enzymes for de novo pyrimidine biosynthesis. To gain more details about the spectrum of metabolites generated from aspartate and subsequently released by cultured astrocytes a (13)C-nuclear magnetic resonance analysis was performed of [U-(13)C]aspartate supplemented incubation media exposed to astroglial cultures. The results show that astrocytes readily metabolize aspartate and release into their culture media (13)C-isotopomers of lactate, glutamine, citrate and alanine. Despite the presence in astroglial cells of two tandem enzymes of pyrimidine biosynthesis and their mRNAs, pyrimidine nucleotide-related heterocyclic compounds such as dihydroorotate and orotate could not be detected in the culture media.
Interfaculty Institute for Biochemistry, University of Tuebingen, Hoppe-Seyler-Str 4, 72076 Tuebingen, Germany.
Radovan
R
Murín
Ghasem
G
Mohammadi
Bhavani S
BS
Kowtharapu
Dieter
D
Leibfritz
Bernd
B
Hamprecht
D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism*; D001253:Astrocytes / Q000378:metabolism*; D001483:Base Sequence; D002247:Carbon Isotopes; D002478:Cells, Cultured; D003470:Culture Media; D017931:DNA Primers; D009682:Magnetic Resonance Spectroscopy; D009419:Nerve Tissue Proteins / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction
D002247:Carbon Isotopes; D003470:Culture Media; D017931:DNA Primers; D009419:Nerve Tissue Proteins; D001224:Aspartic Acid