Gross K L, Hartman W J, Ronnenberg A, Prior R L
U.S. Department of Agriculture, Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111.
J Nutr. 1991 Oct;121(10):1591-9. doi: 10.1093/jn/121.10.1591.
Blood and urine metabolites were measured in two experiments for young (2-mo-old) and aged (20-mo-old) male Sprague-Dawley rats fed arginine-devoid diets made isonitrogenous to a control 1.12% arginine diet by adding alanine or glycine. Diet, fed for 7 or 13 d, had little effect on urinary or plasma ammonia and urea. Urinary orotate excretion was more than 40-fold higher in rats fed the arginine-deficient diets (P less than 0.01) in both experiments. Source of nonessential N (alanine or glycine) in the arginine-deficient diets did not alter orotic acid excretion or plasma or urine ammonia or urea. Changes in plasma arginine, alanine and glycine concentrations reflected the levels of these amino acids in the diet. Tissue ornithine levels reflected dietary arginine level, but tissue citrulline was unaffected by dietary arginine. Glutamate and glutamine were greater in the plasma and liver of rats fed arginine-deficient diets. Plasma concentrations of glutamate and glutamine were positively correlated with urinary orotic acid excretion (P less than 0.05) and ornithine and arginine were negatively correlated with orotic acid excretion (P less than 0.01). Increased tissue glutamine may be related to the greater orotate excretion in rats fed arginine-devoid diets. The metabolic responses to dietary arginine deficiency were similar in young and aged rats. In general, concentrations of amino acids in plasma, liver and spleen were higher in aged rats.
在两项实验中，对两组雄性斯普拉格-道利大鼠（2月龄的幼鼠和20月龄的老龄鼠）的血液和尿液代谢物进行了测量。这两组大鼠均喂食缺乏精氨酸的日粮，通过添加丙氨酸或甘氨酸使其与对照的1.12%精氨酸日粮等氮。日粮喂养7天或13天，对尿液或血浆中的氨和尿素影响不大。在两项实验中，喂食精氨酸缺乏日粮的大鼠尿液乳清酸排泄量均高出40多倍（P<0.01）。精氨酸缺乏日粮中非必需氮的来源（丙氨酸或甘氨酸）并未改变乳清酸排泄量或血浆或尿液中的氨或尿素。血浆中精氨酸、丙氨酸和甘氨酸浓度的变化反映了日粮中这些氨基酸的水平。组织鸟氨酸水平反映了日粮精氨酸水平，但组织瓜氨酸不受日粮精氨酸的影响。喂食精氨酸缺乏日粮的大鼠血浆和肝脏中的谷氨酸和谷氨酰胺含量更高。血浆中谷氨酸和谷氨酰胺浓度与尿液乳清酸排泄量呈正相关（P<0.05），鸟氨酸和精氨酸与乳清酸排泄量呈负相关（P<0.01）。喂食缺乏精氨酸日粮的大鼠组织谷氨酰胺增加可能与乳清酸排泄量增加有关。幼鼠和老龄鼠对日粮精氨酸缺乏的代谢反应相似。一般来说，老龄大鼠血浆、肝脏和脾脏中的氨基酸浓度更高。
