Berard M P, Hankard R, Cynober L
Laboratoire de Biochimie A, Hôtel-Dieu, Paris, France.
Clin Nutr. 2001 Oct;20(5):407-14. doi: 10.1054/clnu.2001.0466.
The aim of this study was to determine the metabolism and the tolerance of a new amino acid (AA) solution administered under conditions mimicking cyclical parenteral nutrition (PN) in humans. Eight healthy volunteers received peripheral PN for 10 h providing 10.5 mg N x kg(-1) x h(-1) and 2.0 kcal x kg(-1) x h(-1) (glucose-to-lipids ratio: 70/30%). For adaptation, a non-protein energy intake was increased progressively for 90 min; thereafter, AA infusion was started and maintained at a constant rate for 10 h. Plasma and urine concentrations of all the AAs were measured before, during and after the PN. For each given AA, the relation between plasma variations at the steady-state and infusion rate, plasma clearance (Cl), renal clearance (Clr), re-absorption rate (Reab) and, retention rate (Reten) were determined. The nitrogen balance (DeltaN) was calculated during the PN period. The results are presented as means+/-sem. All plasma AA concentrations decreased during the starting period of non-protein energy intake. The plasma AA concentrations reached a steady-state within 3 h upon AA infusion, except for glycine and lysine (6 h). At the steady state, the plasma concentrations of the infused AAs were closely correlated to their infusion rate (y= -18.3+1.5x, r(2)=0.92). The plasma glutamine concentration was maintained during the PN, which indicates that the solution might stimulate the de novo synthesis of this AA. When the PN was stopped, plasma levels of the AAs decreased, most of them returning to their basal levels, or significantly below for lysine (P<0.05), alanine (P<0.05), proline (P<0.01) and glutamine (P<0.05). No volunteer showed any adverse effect during the infusion period. DeltaN was: 0.8+/-0.5 gN/10 h. Metabolic characteristics for essential AAs were: Cl<0.5 l min(-1), Clr <1.5 ml x min(-1) Reab >or= 99%, Reten >or=99% and for non-essential AAs: Cl <0.6 l x min(-1) except aspartate (2.8+/-0.3 l x min(-1)), Clr < 3 ml x min(-1) except glycine (6.8+/-0.7), aspartate (8.2+/-3.5) and histidine (8.8+/-1.3); Reab >or= 98% except glycine (95+/-1), aspartate (94+/-2) and histidine (94+/-1), Reten >or=97% except histidine (94+/-1), glycine (95+/-3). These results indicate that in healthy subjects, the amounts of AAs provided by the new solution were well balanced for an intravenous administration, and so were well utilized without excessive urinary excretion. The present study provides useful metabolic parameters for a further evaluation in disease.
本研究的目的是确定一种新型氨基酸（AA）溶液在模拟人体周期性肠外营养（PN）的条件下的代谢情况和耐受性。八名健康志愿者接受了10小时的外周PN，提供10.5毫克氮×千克⁻¹×小时⁻¹和2.0千卡×千克⁻¹×小时⁻¹（葡萄糖与脂质比例：70/30%）。为了适应，非蛋白质能量摄入量在90分钟内逐渐增加；此后，开始输注AA并以恒定速率维持10小时。在PN之前、期间和之后测量所有AA的血浆和尿液浓度。对于每种给定的AA，确定稳态时血浆变化与输注速率、血浆清除率（Cl）、肾清除率（Clr）、重吸收率（Reab）和保留率（Reten）之间的关系。在PN期间计算氮平衡（ΔN）。结果以平均值±标准误表示。在非蛋白质能量摄入的起始阶段，所有血浆AA浓度均下降。输注AA后3小时内，血浆AA浓度达到稳态，但甘氨酸和赖氨酸除外（6小时）。在稳态时，输注AA的血浆浓度与其输注速率密切相关（y = -18.3 + 1.5x，r² = 0.92）。PN期间血浆谷氨酰胺浓度保持稳定，这表明该溶液可能刺激了这种AA的从头合成。当PN停止时，AA的血浆水平下降，大多数恢复到基础水平，或赖氨酸（P<0.05）、丙氨酸（P<0.05）、脯氨酸（P<0.01）和谷氨酰胺（P<0.05）显著低于基础水平。在输注期间，没有志愿者出现任何不良反应。ΔN为：0.8±0.5克氮/10小时。必需AA的代谢特征为：Cl<0.5升/分钟，Clr<1.5毫升/分钟，Reab≥99%，Reten≥99%；非必需AA的代谢特征为：Cl<0.6升/分钟，天冬氨酸除外（2.8±0.3升/分钟），Clr<3毫升/分钟，甘氨酸、天冬氨酸和组氨酸除外（甘氨酸：6.8±0.7，天冬氨酸：8.2±3.5，组氨酸：8.8±1.3）；Reab≥98%，甘氨酸、天冬氨酸和组氨酸除外（甘氨酸：95±1，天冬氨酸：94±2，组氨酸：94±1），Reten≥97%，组氨酸除外（94±1），甘氨酸（95±3）。这些结果表明，在健康受试者中，新溶液提供的AA量对于静脉给药而言平衡良好，因此得到了充分利用，且无过多尿液排泄。本研究为疾病的进一步评估提供了有用的代谢参数。
