Salloum R M, Souba W W, Fernandez A, Stevens B R
Department of Surgery, University of Florida College of Medicine, Gainesville 32610.
J Surg Res. 1990 Jun;48(6):635-8. doi: 10.1016/0022-4804(90)90244-v.
The effects of a glutamine-enriched diet on the transport of glutamine across brush border membrane vesicles (BBMV) from the rat jejunum were studied to gain further insight into the effects of diet on regulating gut glutamine utilization. Following fasting, rats were randomized to one of three nutritionally complete elemental diets supplemented with glutamine, glutamate, or glycine (control). Brush border membrane vesicles were prepared by a Mg2+ aggregation/differential centrifugation technique and uptake of radioactive [3H]glutamine by the BBMV was studied using a rapid mixing/filtration technique. BBMVs from all test diet groups were enriched in alkaline phosphatase 14-fold. [3H]Glutamine uptake courses for all groups demonstrated sodium dependency, overshoots, and similar 2-hr equilibrium values. Vesicles from animals fed the glutamine-enriched diet had a 75% increase in glutamine uptake compared to those of the control diet and a 250% increase compared to those of the glutamate-enriched diet (P less than 0.05). alpha-Methylamino isobutyric acid and glycine did not significantly inhibit total [3H]glutamine uptake, whereas asparagine and glutamine inhibited total [3H]glutamine uptake compared to the mannitol control. The brush border appears to possess the glutamine selective System N transporter, the activity of which can be stimulated by providing dietary glutamine.
研究了富含谷氨酰胺的饮食对大鼠空肠刷状缘膜囊泡（BBMV）中谷氨酰胺转运的影响，以进一步了解饮食对调节肠道谷氨酰胺利用的作用。禁食后，将大鼠随机分为三组，分别给予补充谷氨酰胺、谷氨酸或甘氨酸的三种营养完全的要素饮食（对照组）。采用Mg2+聚集/差速离心技术制备刷状缘膜囊泡，并使用快速混合/过滤技术研究BBMV对放射性[3H]谷氨酰胺的摄取。所有试验饮食组的BBMV中碱性磷酸酶含量均富集了14倍。所有组的[3H]谷氨酰胺摄取过程均表现出钠依赖性、过冲现象以及相似的2小时平衡值。与对照组饮食相比，喂食富含谷氨酰胺饮食的动物的囊泡对谷氨酰胺的摄取增加了75%，与富含谷氨酸饮食的动物的囊泡相比增加了250%（P<0.05）。α-甲基氨基异丁酸和甘氨酸对总[3H]谷氨酰胺摄取没有显著抑制作用，而与甘露醇对照组相比，天冬酰胺和谷氨酰胺抑制了总[3H]谷氨酰胺摄取。刷状缘似乎拥有谷氨酰胺选择性系统N转运体，提供膳食谷氨酰胺可刺激其活性。
