Bennet W M, Connacher A A, Scrimgeour C M, Jung R T, Rennie M J
Department of Anatomy, University of Dundee, United Kingdom.
Am J Physiol. 1990 Aug;259(2 Pt 1):E185-94. doi: 10.1152/ajpendo.1990.259.2.E185.
The effect of insulin on leg and whole body protein turnover was determined by leg exchange and plasma kinetics of [15N]phenylalanine and [1-13C]leucine during amino acid (AA) sufficiency. Eight healthy subjects were studied during AA infusion alone and during infusion of glucose and insulin (0.29 nmol.m-2.min-1) with additional AA. Insulin strongly stimulated the positive leg AA balance seen with AA (AA alone, 2.6 +/- 6.1 vs. insulin + AA, 33.1 +/- 5.8 nmol phenylalanine . 100 g leg-1.min-1; P less than 0.001). Phenylalanine uptake by leg tissues rose during insulin plus AA (47.3 +/- 11.5 vs. 73.1 +/- 7.3 nmol. 100 g-1.min-1; P = 0.022) but with only a slight reduction in leg phenylalanine release (44.7 +/- 8.1 vs. 40.0 +/- 7.9 nmol.100 g-1.min-1). Leg nonoxidative leucine plus alpha-ketoisocaproate (KIC) uptake was increased slightly with insulin (129 +/- 26 vs. 146 +/- 21 nmol.100 g-1. min-1), but leg leucine oxidation increased fourfold (P = 0.012). Leg leucine plus KIC release was reduced by insulin (120 +/- 17 vs. 84 +/- 10 nmol.100 g-1.min-1; P = 0.005); endogenous leucine appearance of leucine and phenylalanine decreased with insulin (leucine, 1.97 +/- 0.08 vs. 1.65 +/- 0.10; phenylalanine, 0.76 +/- 0.03 vs. 0.54 +/- 0.08 mumols.kg-1.min-1; P less than 0.02). The results suggest that insulin, given with sufficient amino acids, may stimulate leg and whole body protein balance by mechanisms including stimulation of protein synthesis and inhibition of protein breakdown.
在氨基酸（AA）充足的情况下，通过腿部[¹⁵N]苯丙氨酸和[¹ - ¹³C]亮氨酸的交换及血浆动力学来测定胰岛素对腿部和全身蛋白质周转的影响。对8名健康受试者在单独输注AA期间以及输注葡萄糖和胰岛素（0.29 nmol·m⁻²·min⁻¹）并补充额外AA期间进行了研究。胰岛素强烈刺激了在输注AA时观察到的腿部AA正平衡（单独输注AA时为2.6±6.1，而胰岛素 + AA时为33.1±5.8 nmol苯丙氨酸·100 g腿部⁻¹·min⁻¹；P＜0.001）。在胰岛素加AA期间，腿部组织对苯丙氨酸的摄取增加（47.3±11.5对73.1±7.3 nmol·100 g⁻¹·min⁻¹；P = 0.022），但腿部苯丙氨酸释放仅略有减少（44.7±8.1对40.0±7.9 nmol·100 g⁻¹·min⁻¹）。胰岛素使腿部非氧化亮氨酸加α - 酮异己酸（KIC）的摄取略有增加（129±26对146±21 nmol·100 g⁻¹·min⁻¹），但腿部亮氨酸氧化增加了四倍（P = 0.012）。胰岛素使腿部亮氨酸加KIC的释放减少（120±17对84±10 nmol·100 g⁻¹·min⁻¹；P = 0.005）；亮氨酸和苯丙氨酸的内源性亮氨酸出现量随胰岛素而降低（亮氨酸，1.97±0.08对1.65±0.10；苯丙氨酸，0.76±0.03对0.54±0.08 μmol·kg⁻¹·min⁻¹；P＜0.02）。结果表明，在给予充足氨基酸的情况下，胰岛素可能通过包括刺激蛋白质合成和抑制蛋白质分解在内的机制来刺激腿部和全身蛋白质平衡。
