Burke J F, Wolfe R R, Mullany C J, Mathews D E, Bier D M
Ann Surg. 1979 Sep;190(3):274-85. doi: 10.1097/00000658-197909000-00002.
Glucose and leucine metabolism in 18 severely burned patients were studied using the primed constant infusion of U-13C-glucose and 1-13C-leucine, respectively. The leucine data were used to calculate rates of whole-body protein synthesis. In four additional burn patients and seven normal controls, the effects of exogenously infused insulin on the metabolism of infused glucose were evaluated. Also, the effect on leucine metabolism of adding insulin to infused glucose was tested and rates of protein synthesis were calculated. The protein studies were divided into two groups depending on the rate of glucose infusion. Protein synthesis was 4.3 + 0.54 g protein/kg/day during the lower infusion rates (1.4--4.5 mg/kg/min) and 5.17 + 0.19 g protein/kg/day during the higher infusion rates (4.7--9.3 mg/kg/min) (statistically different, p less than 0.05). However, when the high infusion rate group was divided into two subgroups (high, 4.7--6.8 mg/kg/min, and very high, 7.03--9.31 mg/kg/min), there was no difference in the rate of protein synthesis. When U-13C-glucose was infused during varying rates of unlabeled glucose infusion, we found that the per cent of CO2 coming from the direct oxidation of glucose rose rapidly at the lower infusion rates but reached a plateau at approximately 55% as the infusion rates exceeded 5 mg/kg/min. Addition of insulin did not affect the rate of glucose oxidation but did seem to exert a stimulatory effect on protein synthesis. It was concluded that there appears to be a maximal rate of glucose infusion, beyond which physiologically significant increases in protein synthesis and direct oxidation of glucose cannot be expected. Furthermore, there appears to be a physiological cost of exceeding the optimal glucose infusion rate, as indicated by increased rates of CO2 production during infusion as well as large fat deposits in the liver at autopsy in patients infused with large amounts of glucose.
分别采用U-13C-葡萄糖和1-13C-亮氨酸的预充恒速输注法，对18例重度烧伤患者的葡萄糖和亮氨酸代谢进行了研究。亮氨酸数据用于计算全身蛋白质合成速率。在另外4例烧伤患者和7例正常对照中，评估了外源性输注胰岛素对输注葡萄糖代谢的影响。此外，还测试了在输注葡萄糖中添加胰岛素对亮氨酸代谢的影响，并计算了蛋白质合成速率。根据葡萄糖输注速率，蛋白质研究分为两组。在较低输注速率（1.4--4.5mg/kg/min）时，蛋白质合成速率为4.3 + 0.54g蛋白质/kg/天，在较高输注速率（4.7--9.3mg/kg/min）时为5.17 + 0.19g蛋白质/kg/天（差异有统计学意义，p小于0.05）。然而，当高输注速率组分为两个亚组（高，4.7--6.8mg/kg/min，和非常高，7.03--9.31mg/kg/min）时，蛋白质合成速率没有差异。当在不同速率的未标记葡萄糖输注期间输注U-13C-葡萄糖时，我们发现来自葡萄糖直接氧化的CO2百分比在较低输注速率时迅速上升，但当输注速率超过5mg/kg/min时，在约55%处达到平台期。添加胰岛素不影响葡萄糖氧化速率，但似乎对蛋白质合成有刺激作用。得出的结论是，似乎存在一个最大葡萄糖输注速率，超过该速率，蛋白质合成和葡萄糖直接氧化在生理上不会有显著增加。此外，超过最佳葡萄糖输注速率似乎存在生理代价，这表现为输注期间CO2产生速率增加以及在尸检时输注大量葡萄糖的患者肝脏中有大量脂肪沉积。
