Zimmermann-Telschow H, Müller-Wecker H
Hoppe Seylers Z Physiol Chem. 1976 May;357(5):695-706.
Nutrition experiments with various levels of calorie and protein intake were carried out on five healthy young men. Three series of experiments with two persons each were undertaken for periods up to 14 days. The first part of each experiment, with 1100 to 1500 kcal/day, was immediately followed by the second part, with 3500 to 2300 kcal/day. The concentrations of insulin, free fatty acids, glucose and amino acids were determined in the morning, fasted blood. The nitrogen balance was also determined. When insufficient carbohydrate intake is coupled with normal and high protein content of the food, there is interindividually an initial drop in the insulin concentration. Regardless of the absolute insulin concentration, this drop causes an increase in the free fatty acids and the branched-chain amino acids, together with a decrease in the concentrations of alanine and glycine (threonine) in the blood and a negative nitrogen balance. The high concentrations of branched-chain amino acids and the low threonine concentrations might be involved as feedback regulators in the further regulation of the gluconeogenic metabolism. When carbohydrate calories are added to the diet, a simultaneous decrease in the free fatty acids and branched-chain amino acids and increase in the blood concentrations of insulin, alanine, glycine and threonine within 24 to 48 h are only observed with 3500 kcal/day and 0.8 to 1.4 g protein per kg body weight. A positive nitrogen balance, however, is only observed with 1.4 g protein per kg body weight, regardless of the relative changes in the insulin level, while the increase in alanine and decrease in branched-chain amino acids (valine) are greatest at 0.8 g protein per kg body weight and day. In spite of the high glucose level, the falling insulin level provokes counter-regulatory processes in which the low concentrations of branched-chain amino acids and the high threonine (alanine) concentrations may play a role.
对五名健康年轻男性进行了不同热量和蛋白质摄入量水平的营养实验。进行了三个系列的实验，每个系列两人，为期长达14天。每个实验的第一部分，每天摄入1100至1500千卡热量，紧接着是第二部分，每天摄入3500至2300千卡热量。在早晨空腹血液中测定胰岛素、游离脂肪酸、葡萄糖和氨基酸的浓度。还测定了氮平衡。当碳水化合物摄入量不足且食物中蛋白质含量正常和较高时，个体间胰岛素浓度会出现初始下降。无论胰岛素的绝对浓度如何，这种下降都会导致游离脂肪酸和支链氨基酸增加，同时血液中丙氨酸和甘氨酸（苏氨酸）浓度降低以及负氮平衡。高浓度的支链氨基酸和低浓度的苏氨酸可能作为反馈调节因子参与糖异生代谢的进一步调节。当在饮食中添加碳水化合物热量时，仅在每天摄入3500千卡热量且每千克体重摄入0.8至1.4克蛋白质的情况下，才会在24至48小时内观察到游离脂肪酸和支链氨基酸同时减少，以及血液中胰岛素、丙氨酸、甘氨酸和苏氨酸浓度增加。然而，只有在每千克体重摄入1.4克蛋白质时才会观察到正氮平衡，无论胰岛素水平的相对变化如何，而丙氨酸增加和支链氨基酸（缬氨酸）减少在每千克体重每天摄入0.8克蛋白质时最为明显。尽管血糖水平较高，但胰岛素水平下降会引发反调节过程，其中低浓度的支链氨基酸和高浓度的苏氨酸（丙氨酸）可能发挥作用。
