Gay L J, Schneiter P, Schutz Y, Di Vetta V, Jéquier E, Tappy L
Institute of Physiology, Faculty of Medicine, Lausanne University, Switzerland.
Diabetologia. 1994 May;37(5):517-23. doi: 10.1007/s001250050141.
A novel approach to the study of hepatic glycogen kinetics and fractional gluconeogenesis in vivo is described. Ten healthy female subjects were fed an iso-caloric diet containing 55% carbohydrate energy with a 13C abundance of 1.083 atom percent for a 3-day baseline period; then, a diet of similar composition, but providing carbohydrate with a 13C abundance of 1.093 atom percent was started and continued for 5 days. Resting respiratory gas exchanges, urinary nitrogen excretion, breath 13CO2 and plasma 13C glucose were measured every morning in the fasting state. The enrichment in 13C of hepatic glycogen was calculated from these measured data. 13C glycogen enrichment increased after switching to a 13C enriched carbohydrate diet, and was identical to the 13C enrichment of dietary carbohydrates after 3 days. The time required to renew 50% of hepatic glycogen, as determined from the kinetics of 13C glycogen enrichment, was 18.9 +/- 3.6 h. Fractional gluconeogenesis, as determined from the difference between the enrichments of glucose oxidized originating from hepatic glycogen and plasma glucose 13C was 50.8 +/- 5.3%. This non-invasive method will allow the study of hepatic glycogen metabolism in insulin-resistant patients.
本文描述了一种研究体内肝糖原动力学和糖异生分数的新方法。10名健康女性受试者在3天的基线期内摄入等热量饮食，其中碳水化合物能量占55%，13C丰度为1.083原子百分比；然后，开始摄入成分相似但碳水化合物13C丰度为1.093原子百分比的饮食，并持续5天。每天早晨在空腹状态下测量静息呼吸气体交换、尿氮排泄、呼出的13CO2和血浆13C葡萄糖。根据这些测量数据计算肝糖原的13C富集度。转换为富含13C的碳水化合物饮食后，13C糖原富集度增加，3天后与饮食碳水化合物的13C富集度相同。根据13C糖原富集动力学确定，更新50%肝糖原所需的时间为18.9±3.6小时。根据肝糖原氧化产生的葡萄糖和血浆葡萄糖13C富集度之间的差异确定的糖异生分数为50.8±5.3%。这种非侵入性方法将有助于研究胰岛素抵抗患者的肝糖原代谢。
