Alves Tiago Cardoso, Nunes Patrícia Maria, Palmeira Carlos Marques, Jones John Griffith, Carvalho Rui Albuquerque
Department of Biochemistry, Faculty of Sciences and Technology, University of Coimbra, Coimbra, Portugal.
NMR Biomed. 2008 May;21(4):337-44. doi: 10.1002/nbm.1195.
The gluconeogenic contribution to glucose production in livers isolated from rats fasted for 24 h was determined by 13C-NMR isotopomer distribution analysis of secreted glucose enriched from 99% [13C]bicarbonate (n = 4) and 99% [1-13C]lactate (n = 4). Experiments with 3% 2H2O were also performed, allowing the gluconeogenic contribution to be measured by the relative 2H enrichments at positions 5 and 2 of glucose. From 13C-NMR analyses, the contribution of gluconeogenesis to glucose output was estimated to be 93 +/- 3% for [13C]bicarbonate perfusion and 91 +/- 3% for [1-13C]lactate perfusion, in good agreement with the 2H-NMR analysis of the gluconeogenic contribution to glucose production (100 +/- 1% and 99 +/- 1%, respectively) and consistent with the expected negligible contribution from glycogenolysis. These results indicate that 13C-NMR analysis of glucose 13C-isotopomer distribution from either [13C]bicarbonate or [1-13C]lactate precursor provides realistic estimates of the gluconeogenic contribution to hepatic glucose output.
通过对用99%[¹³C]碳酸氢盐（n = 4）和99%[1-¹³C]乳酸盐（n = 4）富集的分泌葡萄糖进行¹³C-NMR同位素异构体分布分析，测定了从禁食24小时的大鼠分离的肝脏中糖异生对葡萄糖生成的贡献。还进行了3% ²H₂O的实验，通过葡萄糖5位和2位的相对²H富集来测定糖异生的贡献。根据¹³C-NMR分析，对于[¹³C]碳酸氢盐灌注，糖异生对葡萄糖输出的贡献估计为93±3%，对于[1-¹³C]乳酸盐灌注为91±3%，这与糖异生对葡萄糖生成贡献的²H-NMR分析结果（分别为100±1%和99±1%）高度一致，并且与糖原分解预期的可忽略不计的贡献相符。这些结果表明，对来自[¹³C]碳酸氢盐或[1-¹³C]乳酸盐前体的葡萄糖¹³C-同位素异构体分布进行¹³C-NMR分析，能够对糖异生对肝脏葡萄糖输出的贡献做出实际估计。
