Denne S C, Kalhan S C
Am J Physiol. 1986 Jul;251(1 Pt 1):E71-7. doi: 10.1152/ajpendo.1986.251.1.E71.
Total carbohydrate oxidation, plasma glucose oxidation, and glucose carbon recycling were measured in 11 fasting newborns using a constant infusion of D-[U-13C]glucose combined with respiratory calorimetry. The "true" rate of glucose appearance (Ra) was quantified from the enrichment of the nonrecycling tracer species (m + 6), while the "apparent" rate of glucose appearance was quantified from the enrichment of glucose C - 1. The plasma glucose concentration remained constant at approximately 50 mg/dl (2.8 mM) throughout the study. The true rate of glucose production was 5.02 +/- 0.41 mg X kg-1 X min-1, (means +/- SD). Glucose was oxidized at a rate of 2.67 +/- 0.34 mg X kg-1 X min-1 and represented 53% of the glucose turnover. Recycling of glucose carbon represented 36% of the glucose production rate, or 1.87 +/- 0.74 mg X kg-1 X min-1. The oxidation of plasma glucose provided 15.8 +/- 2.0 kcal X kg-1 X day-1, whereas total carbohydrate oxidation (measured by respiratory calorimetry) provided 19.9 +/- 6.6 kcal X kg X day. The data indicate that 1) recycling of glucose carbon accounts for about one-third of glucose production, demonstrating active gluconeogenesis in the fasting newborn; 2) the oxidation of plasma glucose represents only 80% of total carbohydrate oxidation, the remaining 20% possibly representing the local oxidation of tissue glycogen stores; and 3) as the measured rate of glucose oxidation will be insufficient to supply the entire calculated cerebral metabolic requirements, these data suggest that fuels in addition to glucose may be important for cerebral metabolism in the fasting human newborn.
采用持续输注D-[U-¹³C]葡萄糖结合呼吸量热法，对11名空腹新生儿的总碳水化合物氧化、血浆葡萄糖氧化和葡萄糖碳循环进行了测量。通过非循环示踪物质（m + 6）的富集来定量葡萄糖出现的“真实”速率（Ra），而通过葡萄糖C-1的富集来定量葡萄糖出现的“表观”速率。在整个研究过程中，血浆葡萄糖浓度保持在约50mg/dl（2.8mM）不变。葡萄糖产生的真实速率为5.02±0.41mg·kg⁻¹·min⁻¹（均值±标准差）。葡萄糖的氧化速率为2.67±0.34mg·kg⁻¹·min⁻¹，占葡萄糖周转率的53%。葡萄糖碳的循环占葡萄糖产生速率的36%，即1.87±0.74mg·kg⁻¹·min⁻¹。血浆葡萄糖的氧化提供了15.8±2.0kcal·kg⁻¹·day⁻¹，而总碳水化合物氧化（通过呼吸量热法测量）提供了19.9± 6.6kcal·kg⁻¹·day⁻¹。这些数据表明：1）葡萄糖碳的循环约占葡萄糖产生量的三分之一，表明空腹新生儿存在活跃的糖异生作用；2）血浆葡萄糖的氧化仅占总碳水化合物氧化的80%，其余20%可能代表组织糖原储备的局部氧化；3）由于所测得的葡萄糖氧化速率不足以满足整个计算出的大脑代谢需求，这些数据表明除葡萄糖外的其他燃料可能对空腹人类新生儿的大脑代谢很重要。
