James J H, Fischer J E
Pharmacology. 1981;22(1):1-7. doi: 10.1159/000137466.
The movement of neutral amino acids across the blood-brain barrier is bidirectional, however, blood to brain transport is much better characterized than brain to blood transport. Available evidence points to the existence of a single transport system (system L) at the luminal capillary surface. The properties of this system place constraints on possible mechanisms of regulating blood-brain neutral amino acid transport activity. One property, mediation of exchange transport, suggests that amino acid influx is coupled to efflux, particularly efflux of glutamine, synthesized in glial astrocytes from ammonia and glutamic acid. Such a coupling could account for increased blood-brain neutral amino acid transport in liver disease and decreased transport activity after treatment with methionine sulfoximine, a glutamine synthetase inhibitor.
中性氨基酸在血脑屏障间的转运是双向的，然而，从血液到脑的转运比从脑到血液的转运特征更为明确。现有证据表明，在管腔毛细血管表面存在单一的转运系统（系统L）。该系统的特性对调节血脑中性氨基酸转运活性的可能机制构成了限制。其中一个特性，即交换转运的介导作用，表明氨基酸的内流与外流相偶联，尤其是与在胶质星形细胞中由氨和谷氨酸合成的谷氨酰胺的外流相偶联。这种偶联可以解释在肝脏疾病中血脑中性氨基酸转运增加以及在用谷氨酰胺合成酶抑制剂甲硫氨酸亚砜胺治疗后转运活性降低的现象。
