Caumo A, Homan M, Katz H, Cobelli C, Rizza R
Department of Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA.
Am J Physiol. 1995 Sep;269(3 Pt 1):E557-67. doi: 10.1152/ajpendo.1995.269.3.E557.
The present studies were undertaken to determine whether 1) the cold- and hot-GINF techniques used with Steele's model provide equivalent estimates of the rates of glucose appearance (R(a)) and disappearance (R(d)) in the presence of physiological changes in glucose and insulin concentrations, 2) the conditions for the best estimation of R(a) are the same as those for R(d), 3) the magnitude of error (if present) differs in diabetic and nondiabetic subjects, and 4) situations exist in which the knowledge of R(d) allows inferences to be made on whole body glucose uptake. To do so we performed experiments in non-insulin-dependent diabetes mellitus and nondiabetic subjects using simultaneous infusions of [6-3H]glucose and [6-14C]glucose; glucose and insulin were infused to mimic normal postprandial glucose and insulin profiles; the infused glucose contained [6-14C]glucose but not [6-3H]glucose. Compared with the hot-GINF method, the traditional cold-GINF method underestimated (P < 0.05) R(a) and R(d) by 10-15% and hepatic glucose release by 25-50% during the 1st h of the study, with the magnitude of error being the same in both diabetic and nondiabetic subjects. Error analysis demonstrated that errors in R(a) and R(d) have different analytic expressions containing common structural but different volume errors. Both R(a) and R(d) can be accurately measured in diabetic and nondiabetic subjects if glucose specific activity is kept constant and the volume of the accessible pool is used to calculate glucose disappearance. The relationship between R(d) and whole body glucose uptake was also derived. Although R(d) can be determined by relying on measurements in the accessible pool only, the assessment of whole body glucose uptake requires a model of the nonaccessible portion of the glucose system. However, knowledge of R(d) can provide useful insights into the behavior of whole body glucose uptake.
1）在葡萄糖和胰岛素浓度发生生理性变化的情况下，使用Steele模型的冷葡萄糖输注示踪法（cold-GINF）和热葡萄糖输注示踪法（hot-GINF）对葡萄糖出现率（R(a)）和消失率（R(d)）的估计是否等效；2）对R(a)进行最佳估计的条件是否与R(d)相同；3）糖尿病患者和非糖尿病患者中误差的大小（若存在误差）是否不同；4）是否存在这样的情况，即R(d)的相关知识能够用于推断全身葡萄糖摄取情况。为此，我们在非胰岛素依赖型糖尿病患者和非糖尿病受试者中进行了实验，同时输注[6-³H]葡萄糖和[6-¹⁴C]葡萄糖；输注葡萄糖和胰岛素以模拟正常餐后葡萄糖和胰岛素曲线；输注的葡萄糖含有[6-¹⁴C]葡萄糖但不含[6-³H]葡萄糖。与hot-GINF方法相比，传统的cold-GINF方法在研究的第1小时内低估了（P < 0.05）R(a)和R(d) 10%-15%，低估了肝葡萄糖释放25%-50%，糖尿病患者和非糖尿病患者中的误差大小相同。误差分析表明，R(a)和R(d)的误差具有不同的分析表达式，其中包含共同的结构误差但体积误差不同。如果葡萄糖比活保持恒定，并使用可及池的体积来计算葡萄糖消失率，则R(a)和R(d)在糖尿病患者和非糖尿病受试者中均可准确测量。还推导了R(d)与全身葡萄糖摄取之间的关系。虽然仅依靠可及池中的测量就能确定R(d)，但评估全身葡萄糖摄取需要一个葡萄糖系统不可及部分的模型。然而，R(d)的相关知识能够为全身葡萄糖摄取行为提供有用的见解。
