Mass isotopomer study of glutamine oxidation and synthesis in primary culture of astrocytes
Abstract
The metabolism of [1, 2-13C2] acetate via the tricarboxylic acid (TCA) cycle leads to the formation of a number of key mass isotopomers of glutamate. The distribution of these isotopomers which is a function of pyruvate carboxylase, pyruvate dehydrogenase and pyruvate recycling was used to determine the relative anaplerotic flux and glutamine oxidation of astrocytes in culture under different substrate conditions. Combinatory analysis of mass isotopomers formed from the condensation of labeled oxaloacetate with labeled acetyl-CoA was used to determine precursor enrichment and fractional glutamine synthesis. When glucose or glutamine was supplied in the medium, the effective anaplerotic flux (Y') was about 1.5 times that of the TCA cycle flux. Under substrate-limiting conditions, Y' and glutamine synthesis was significantly reduced. A unique feature of the use of [1, 2-13C2] acetate in this study is the formation of singly labeled isotopomer of glutamine in the C4 or C5 position when glutamine is irreversibly loss in net oxidation. We observed very little [4-13C] or [5-13C] glutamine either because of the lack of pyruvate recycling or the lack of pyruvate dehydrogenase activity. The lack of 13C recycling to the C4 and C5 positio...Continue Reading
Citations
Dynamic profiling of the glucose metabolic network in fasted rat hepatocytes using [1,2-13C2]glucose
Related Concepts
Related Feeds
Astrocytes
Astrocytes are glial cells that support the blood-brain barrier, facilitate neurotransmission, provide nutrients to neurons, and help repair damaged nervous tissues. Here is the latest research.