Kalderon B, Gopher A, Lapidot A
FEBS Lett. 1987 Mar 9;213(1):209-14. doi: 10.1016/0014-5793(87)81493-x.
A quantitative analysis of the major metabolic pathways of hepatic glucose synthesis in fasted rats was conducted. [2-13C]Acetate was administered intraintestinally into awake fasted rats. 13C 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%.
对禁食大鼠肝脏葡萄糖合成的主要代谢途径进行了定量分析。将[2-¹³C]乙酸经肠道给予清醒的禁食大鼠。采用¹³C NMR和GC-MS分析来定量谷氨酸、谷氨酰胺、乳酸、丙氨酸以及新合成的肝脏葡萄糖的同位素丰度。通过测量源自乙酰辅酶A的谷氨酸分子中的碳原子与源自草酰乙酸和糖异生底物（如乳酸和丙氨酸）的葡萄糖分子中的碳原子的比例，对三羧酸循环和糖异生的相对活性进行了定量。我们的结果表明，通过三羧酸循环与草酰乙酸池进行“代谢交换”产生的葡萄糖碳的百分比小于7%。
