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A quantitative analysis of the metabolic pathways of hepatic glucose synthesis in vivo with 13 C‐labeled substrates
Author(s) -
Kalderon B.,
Gopher A.,
Lapidot A.
Publication year - 1987
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(87)81493-x
Subject(s) - in vivo , metabolic pathway , chemistry , biochemistry , metabolism , medicine , biology , genetics
A quantitative analysis of the major metabolic pathways of hepatic glucose synthesis in fasted rats was conducted. [2‐ 13 C]Acetate was administered intraintestinally into awake fasted rats. 13 C NMR and GC‐MS analysis were used to quantitate the isotopic enrichments of glutamate, glutamine, lactate, alanine and the newly synthesized liver glucose. By measuring the ratio of carbon atoms in glutamate molecules derived from acetyl‐CoA to carbon atoms in the glucose molecule derived from oxaloacetate and gluconeogenic substrates, such as lactate and alanine, the relative activities of the Krebs cycle and gluconeogenesis were quantified. Our results indicate that the percentage of glucose carbons originating by ‘metabolic exchange’ with the oxaloacetate pool, via the Krebs cycle, is less than 7%.