Hartman W J, Prior R L
U.S. Department of Agriculture, Tufts University, Boston, MA 02111.
J Nutr. 1992 Jul;122(7):1472-82. doi: 10.1093/jn/122.7.1472.
The effect of an arginine-deficient diet on net flux of amino acids across the portal-drained viscera and across the liver was studied in rats. Blood was obtained after food deprivation and 1 and 2 h after a meal of a 1.0% arginine control diet or an arginine-deficient diet containing 3.4% glutamate. The arginine-deficient diet decreased net portal-drained viscera flux of arginine and increased net portal-drained viscera flux of ornithine and proline. However, net portal-drained viscera flux of citrulline (0.35 +/- 0.05 mumol/min) was not influenced by diet; of this rate, 46% (0.16 mumol/min) bypassed the liver and was available for extrahepatic arginine synthesis. However, rats continued to exhibit signs of arginine deficiency such as decreased blood arginine concentrations (by 28%) and increased orotic acid excretion (90-fold). Arterial blood glutamine concentration was 25% higher in rats fed the arginine-deficient diet. In the fed state, net hepatic flux of glutamine was elevated from 0.15 (control) to 1.39 mumol/min, indicating that the liver was a major source of the increased blood glutamine concentrations. Increased production of hepatic glutamine and orotic acid may help rats compensate for dietary arginine deficiency, whereas splanchnic output of citrulline was not increased with dietary arginine deficiency even with a substantial dietary supply of glutamate.
在大鼠中研究了精氨酸缺乏饮食对氨基酸跨门静脉引流内脏和肝脏的净通量的影响。在禁食后以及喂食1.0%精氨酸对照饮食或含3.4%谷氨酸的精氨酸缺乏饮食1小时和2小时后采集血液。精氨酸缺乏饮食降低了精氨酸的门静脉引流内脏净通量，增加了鸟氨酸和脯氨酸的门静脉引流内脏净通量。然而，瓜氨酸的门静脉引流内脏净通量（0.35±0.05μmol/分钟）不受饮食影响；在这个速率中，46%（0.16μmol/分钟）绕过肝脏，可用于肝外精氨酸合成。然而，大鼠仍表现出精氨酸缺乏的迹象，如血液精氨酸浓度降低（28%）和乳清酸排泄增加（90倍）。喂食精氨酸缺乏饮食的大鼠动脉血谷氨酰胺浓度高25%。在进食状态下，谷氨酰胺的肝脏净通量从0.15（对照）升高到1.39μmol/分钟，表明肝脏是血液谷氨酰胺浓度升高的主要来源。肝脏谷氨酰胺和乳清酸产量增加可能有助于大鼠补偿饮食精氨酸缺乏，而即使饮食中谷氨酸供应充足，饮食精氨酸缺乏时瓜氨酸的内脏输出也没有增加。
