Robert J J, Cummins J C, Wolfe R R, Durkot M, Matthews D E, Zhao X H, Bier D M, Young V R
Diabetes. 1982 Mar;31(3):203-11. doi: 10.2337/diab.31.3.203.
The metabolic basis for the reduced glucose tolerance that occurs during aging in humans has been explored with the aid of a primed constant intravenous infusion method of labeled glucose (6-3H; 6,6,2H- and U-13C-glucose). Healthy young adult men and women (24 +/- 3 yr) and elderly men and women (75 +/- 4 yr) participated in a series of studies designed to quantify rates of plasma glucose appearance, oxidation, and recycling while subjects were in the postabsorptive (basal) state and to determine rates of hepatic glucose production and glucose disappearance in response to intravenous glucose at approximately 1 and 2 mg x kg-1min-1 and also 4 mg x kg-1min-1 without or with a simultaneous infusion of insulin to maintain normoglycemia. Basal rates of glucose production were 2.41 +/- 0.06 and 2.18 /+/- 0.05 mg x kg-1min-1 in the young adults and elderly, respectively (P less than 0.05). Recycling of glucose carbon and glucose oxidation rates did not differ significantly between the two age groups. Infusion of unlabeled glucose reduced hepatic glucose production to the same extent in the two groups, indicating that the mechanisms responsible for altered hepatic glucose production with intravenous glucose administration remain intact during human aging. Plasma insulin changes were similar in young adult and elderly subjects receiving 4 mg x kg-1min-1 unlabeled glucose except that the higher plasma glucose levels in the elderly were associated with higher insulin levels. For elderly subjects, the amount of exogenous insulin required to maintain normoglycemia at the 4 mg x kg-1min-1 glucose infusion rate was about twice that necessary in young adults.
借助标记葡萄糖（6-³H；6,6,²H-和U-¹³C-葡萄糖）的首剂量恒速静脉输注法，对人类衰老过程中出现的糖耐量降低的代谢基础进行了探索。健康的年轻成年男性和女性（24±3岁）以及老年男性和女性（75±4岁）参与了一系列研究，旨在量化受试者处于吸收后（基础）状态时血浆葡萄糖的出现率、氧化率和再循环率，并确定静脉输注葡萄糖（约1和2mg·kg⁻¹·min⁻¹以及4mg·kg⁻¹·min⁻¹）时，无论有无同时输注胰岛素以维持正常血糖水平，肝脏葡萄糖生成率和葡萄糖消失率。年轻成年人和老年人的基础葡萄糖生成率分别为2.41±0.06和2.18±0.05mg·kg⁻¹·min⁻¹（P＜0.05）。两个年龄组之间葡萄糖碳的再循环和葡萄糖氧化率没有显著差异。输注未标记葡萄糖在两组中均使肝脏葡萄糖生成减少到相同程度，这表明在人类衰老过程中，静脉输注葡萄糖时导致肝脏葡萄糖生成改变的机制仍然完好。接受4mg·kg⁻¹·min⁻¹未标记葡萄糖的年轻成年受试者和老年受试者的血浆胰岛素变化相似，只是老年人较高的血浆葡萄糖水平与较高的胰岛素水平相关。对于老年受试者，在4mg·kg⁻¹·min⁻¹葡萄糖输注速率下维持正常血糖所需的外源性胰岛素量约为年轻成年人的两倍。
