Giordano M, Castellino P, Carroll C A, DeFronzo R A
Institute of Internal Medicine and Nephrology, Second University of Naples, Italy.
Diabetologia. 1995 Jun;38(6):732-8. doi: 10.1007/BF00401848.
We examined the effects of recombinant human insulin-like growth factor I (IGF-I) and insulin on the plasma amino acid (AA) profile and leucine kinetics in eight normal subjects. IGF-I was infused at 52 pmol.kg-1.min-1, in combination with prime-continuous [1-14C] leucine infusion, to obtain steady-state plasma concentrations of total (54 +/- 3 nmol/l) and free (7.3 +/- 1 nmol/l) IGF-I (study 1). In response to IGF-I, plasma AA levels declined by 37 +/- 3% (1975 +/- 198 to 1368 +/- 120 mumol/l) and total branched chain amino acids (BCAA) declined by 34 +/- 3% (390 +/- 21 to 256 +/- 13 mumol/l). This hypoaminoacidaemic effect was associated with a decline in endogenous leucine flux of 17 +/- 2% (1.88 +/- 0.05 to 1.57 +/- 0.04 mumol.kg-1.min-1) and leucine oxidation of 17 +/- 1% (0.31 +/- 0.02 vs 0.26 +/- 0.02 mumol.kg-1.min-1) (both p < 0.01 vs basal). The same subjects underwent a second study (study 2) in which insulin was infused at 6.22 pmol.kg-1.min-1 to obtain a steady-state plasma insulin concentration of 530 +/- 25 pmol/l while maintaining euglycaemia. The infusion rate was designed to match the declines in plasma BCAA levels and leucine turnover observed during IGF-I infusion. The rates of glucose infusion necessary to maintain euglycaemia during IGF-I and insulin infusion were 4.9 +/- 1.0 and 7.8 +/- 0.6 mg.kg-1.min-1, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
我们研究了重组人生长激素释放因子I（IGF-I）和胰岛素对8名正常受试者血浆氨基酸（AA）谱及亮氨酸动力学的影响。以52 pmol·kg⁻¹·min⁻¹的速率输注IGF-I，并联合首剂-持续输注[1-¹⁴C]亮氨酸，以获得总IGF-I（54±3 nmol/l）和游离IGF-I（7.3±1 nmol/l）的稳态血浆浓度（研究1）。作为对IGF-I的反应，血浆AA水平下降了37±3%（从1975±198降至1368±120 μmol/l），总支链氨基酸（BCAA）下降了34±3%（从390±21降至256±13 μmol/l）。这种低氨基酸血症效应与内源性亮氨酸通量下降17±2%（从1.88±0.05降至1.57±0.04 μmol·kg⁻¹·min⁻¹）和亮氨酸氧化下降17±1%（从0.31±0.02降至0.26±0.02 μmol·kg⁻¹·min⁻¹）相关（两者与基础值相比p<0.01）。相同受试者进行了第二项研究（研究2），其中以6.22 pmol·kg⁻¹·min⁻¹的速率输注胰岛素，以获得530±25 pmol/l的稳态血浆胰岛素浓度，同时维持血糖正常。输注速率的设计旨在匹配IGF-I输注期间观察到的血浆BCAA水平下降和亮氨酸周转率。在IGF-I和胰岛素输注期间维持血糖正常所需的葡萄糖输注速率分别为4.9±1.0和7.8±0.6 mg·kg⁻¹·min⁻¹。（摘要截选至250字）
