Enteral arginase II provides ornithine for citrulline synthesis.
Enteral arginase II provides ornithine for citrulline synthesis.
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肠内精氨酸酶 II 为瓜氨酸合成提供鸟氨酸。
DOI：
10.1152/ajpendo.00413.2010
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
Lee,Brendan
中科院分区：
文献类型：
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作者：
Marini,JuanC;Keller,Bettina;Didelija,InkaCajo;Castillo,Leticia;Lee,Brendan
在小肠中由精氨酸合成瓜氨酸取决于鸟氨酸的供应。为了验证这一假设，即精氨酸酶II在瓜氨酸合成的鸟氨酸供应中起着核心作用，通过在精氨酸酶II敲除小鼠（AII−/−）和野生型小鼠（WT）中使用多示踪剂稳定同位素方案，确定了饮食中精氨酸、谷氨酰胺和脯氨酸的贡献。由于鸟氨酸的可用性降低，缺乏精氨酸酶II导致瓜氨酸出现率降低（121与137 μmol·kg−1·h−1）;补充鸟氨酸能够将AII−/−小鼠的瓜氨酸产生率恢复到与WT小鼠相当的水平。在饮食瓜氨酸前体的利用方面存在显著差异。由于缺乏精氨酸酶II，日粮精氨酸对瓜氨酸合成的贡献从45 μmol·kg−1·h− 1降低到10 μmol·kg− 1。在AII−/−小鼠（WT = 25 μmol·kg−1·h−1）中未观察到精氨酸的肠内利用，并且转基因小鼠中通过血浆鸟氨酸的饮食精氨酸贡献减少（20 vs. 13 μmol·kg−1·h−1）。AII−/−小鼠的谷氨酰胺和脯氨酸利用率高于WT小鼠（分别为20和13 μ mol·kg−1·h− 1，1.4和3.7 μmol·kg−1·h−1）。谷氨酰胺和脯氨酸的大部分贡献是肠内的，而不是通过血浆鸟氨酸。小肠粘膜中存在的鸟氨酸酶亚型具有为瓜氨酸合成提供鸟氨酸的作用。缺乏精氨酸酶II会导致血浆中的鸟氨酸以及膳食中的谷氨酰胺和脯氨酸对瓜氨酸的合成做出更大的贡献。
The synthesis of citrulline from arginine in the small intestine depends on the provision of ornithine. To test the hypothesis that arginase II plays a central role in the supply of ornithine for citrulline synthesis, the contribution of dietary arginine, glutamine, and proline was determined by utilizing multitracer stable isotope protocols in arginase II knockout (AII−/−) and wild-type (WT) mice. The lack of arginase II resulted in a lower citrulline rate of appearance (121 vs. 137 μmol·kg−1·h−1) due to a reduced availability of ornithine; ornithine supplementation was able to restore the rate of citrulline production in AII−/−to levels comparable with WT mice. There were significant differences in the utilization of dietary citrulline precursors. The contribution of dietary arginine to the synthesis of citrulline was reduced from 45 to 10 μmol·kg−1·h−1due to the lack of arginase II. No enteral utilization of arginine was observed in AII−/−mice (WT = 25 μmol·kg−1·h−1), and the contribution of dietary arginine through plasma ornithine was reduced in the transgenic mice (20 vs. 13 μmol·kg−1·h−1). Dietary glutamine and proline utilization were greater in AII−/−than in WT mice (20 vs. 13 and 1.4 vs. 3.7 μmol·kg−1·h−1, respectively). Most of the contribution of glutamine and proline was enteral rather than through plasma ornithine. The arginase isoform present in the small intestinal mucosa has the role of providing ornithine for citrulline synthesis. The lack of arginase II results in a greater contribution of plasma ornithine and dietary glutamine and proline to the synthesis of citrulline.