AMINO ACID METABOLISM DURING PROLONGED STARVATION
AMINO ACID METABOLISM DURING PROLONGED STARVATION
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DOI：
10.1172/jci106017
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发表时间：
1969-01-01
影响因子：
15.9
通讯作者：
CAHILL, GF
中科院分区：
文献类型：
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作者：
FELIG, P;OWEN, OE;CAHILL, GF
研究了肥胖受试者在长期（5-6周）饥饿期间20种氨基酸的血浆浓度、内脏和肾脏交换以及尿排泄。在吸收后和短暂禁食（36-48 h）的受试者中也研究了内脏氨基酸的摄取，在饥饿的第1周，观察到血浆缬氨酸、亮氨酸、异亮氨酸、蛋氨酸和α-氨基丁酸的短暂增加。在第1个5天后，甘氨酸、苏氨酸和丝氨酸出现延迟的渐进性增加。13种氨基酸最终减少饥饿，但这种减少的幅度是最大的丙氨酸下降最迅速，在第1周的fasting.In所有科目丙氨酸提取的内脏循环在更大程度上比所有其他氨基酸的组合。短暂禁食导致丙氨酸的动-肝静脉差异增加，这是由于提取分数增加。饥饿5-6周后，内脏丙氨酸摄取明显下降，这归因于动脉浓度降低。长时间禁食导致增加甘氨酸利用肾脏和净肾摄取alanine.It的结论是，血浆丙氨酸显着减少是由于增强和优先内脏利用这种氨基酸在早期饥饿导致基板耗尽。低丙氨酸血症的维持最终用于减少内脏对这种关键的生糖氨基酸的摄取，因此是调节机制的重要组成部分，由此在长时间禁食中减少肝再生和蛋白质分解。改变肾脏提取的甘氨酸和丙氨酸是不是由于尿排泄增加，但可能是次要的肾脏recomeogenesis观察到在长期饥饿的速度增加。
Plasma concentration, splanchnic and renal exchange, and urinary excretion of 20 amino acids were studied in obese subjects during prolonged (5-6 wk) starvation. Splanchnic amino acid uptake was also investigated in postabsorptive and briefly (36-48 hr) fasted subjects.A transient increase in plasma valine, leucine, isoleucine, methionine, and α-aminobutyrate was noted during the 1st wk of starvation. A delayed, progressive increase in glycine, threonine, and serine occurred after the 1st 5 days. 13 of the amino acids ultimately decreased in starvation, but the magnitude of this diminution was greatest for alanine which decreased most rapidly during the 1st week of fasting.In all subjects alanine was extracted by the splanchnic circulation to a greater extent than all other amino acids combined. Brief fasting resulted in an increased arterio-hepatic venous difference for alanine due to increased fractional extraction. After 5-6 wk of starvation, a marked falloff in splanchnic alanine uptake was attributable to the decreased arterial concentration. Prolonged fasting resulted in increased glycine utilization by the kidney and in net renal uptake of alanine.It is concluded that the marked decrease in plasma alanine is due to augmented and preferential splanchnic utilization of this amino acid in early starvation resulting in substrate depletion. Maintenance of the hypoalaninemia ultimately serves to diminish splanchnic uptake of this key glycogenic amino acid and is thus an important component of the regulatory mechanism whereby hepatic gluconeogenesis is diminished and protein catabolism is minimized in prolonged fasting. The altered renal extraction of glycine and alanine is not due to increased urinary excretion but may be secondary to the increased rate of renal gluconeogenesis observed in prolonged starvation.