PLASMA ARGININE AND CITRULLINE KINETICS IN ADULTS GIVEN ADEQUATE AND ARGININE-FREE DIETS
PLASMA ARGININE AND CITRULLINE KINETICS IN ADULTS GIVEN ADEQUATE AND ARGININE-FREE DIETS
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DOI：
10.1073/pnas.90.16.7749
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发表时间：
1993-08-15
影响因子：
11.1
通讯作者：
YOUNG, VR
中科院分区：
文献类型：
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作者：
CASTILLO, L;CHAPMAN, TE;YOUNG, VR
精氨酸和瓜氨酸通过血浆的通量以及标记的瓜氨酸向精氨酸的转化率在两项试点研究（总共六名成年受试者）和一项对五名健康年轻男性的饮食研究中进行了估计。这些受试者在第 7 天进行 8 小时（前 3 小时，禁食；最后 5 小时，进食）的连续静脉输注方案之前，分别接受富含精氨酸或不含精氨酸的 L-氨基酸饮食 6 天，使用 L-[胍基-C-13]精氨酸、L-[5,5-H-2(2)]瓜氨酸和 L-[5,5,5-H-2(3)]亮氨酸，作为示踪剂。一项初步研究表明，与[H-2(2)]瓜氨酸相比，用[ureido-C-13]瓜氨酸测定时，瓜氨酸通量高出约20% (P < 0.05)，表明后者示踪剂的循环利用。各个代谢/饮食组的平均瓜氨酸通量约为8-11 mumol.kg-1.hr-1，并且在禁食和进食状态或富含精氨酸和不含精氨酸的时期之间没有显着差异。在富含精氨酸的时期，禁食和进食状态下的精氨酸通量（平均值 +/- SD）分别为 60.2 +/- 5.4 和 73.3 +/- 13.9 mumol.kg-1.hr-1，并且在不含精氨酸期间显着降低（P < 0.05）20-40%，尤其是在进食状态下，这主要是由于膳食精氨酸摄入量的减少进入 等离子体。各组血浆瓜氨酸转化为精氨酸的转化率约为 5.5 mumol.kg-1.hr-1，并且也不受精氨酸摄入量的影响。因此，内源性精氨酸合成对健康成人精氨酸摄入量的急性变化没有明显反应。我们认为精氨酸稳态主要是通过调节精氨酸摄入和/或精氨酸降解的净速率来实现的。
The fluxes of arginine and citrulline through plasma and the rate of conversion of labeled citrulline to arginine were estimated in two pilot studies (with a total of six adult subjects) and in a dietary study with five healthy young men. These latter subjects received an L-amino acid-based diet that was arginine-rich or arginine-free each for 6 days prior to conduct, on day 7, of an 8-hr (first 3 hr, fast; final 5 hr, fed) primed continuous intravenous infusion protocol using L-[guanidino-C-13]arginine, L-[5,5-H-2(2)]citrulline, and L-[5,5,5-H-2(3)]leucine, as tracers. A pilot study indicated that citrulline flux was about 20% higher (P < 0.05) when determined with [ureido-C-13]citrulline compared with [H-2(2)]citrulline, indicating recycling of the latter tracer. Mean citrulline fluxes were about 8-11 mumol.kg-1.hr-1 for the various metabolic/diet groups and did not differ significantly between fast and fed states or arginine-rich and arginine-free periods. Arginine fluxes (mean +/- SD) were 60.2 +/- 5.4 and 73.3 +/- 13.9 mumol.kg-1.hr-1 for fast and fed states during the arginine-rich period, respectively, and were significantly lowered (P < 0.05), by 20-40%, during the arginine-free period, especially for the fed state, where this was due largely to reduced entry of dietary arginine into plasma. The conversion of plasma citrulline to arginine approximated 5.5 mumol.kg-1.hr-1 for the various groups and also was unaffected by arginine intake. Thus, endogenous arginine synthesis is not markedly responsive to acute alterations in arginine intake in healthy adults. We propose that arginine homeostasis is achieved largely via modulating arginine intake and/or the net rate of arginine degradation.