Yudilevich D L, Sepúlveda F V, Bustamante J C, Mann G E
J Neural Transm Suppl. 1979(15):15-27. doi: 10.1007/978-3-7091-2243-3_2.
Amino acid tmransport at the luminal side of brain capillary endothelium and the basal side of salivary epithelium were compared using a nondestructive, first-circulation, paired-tracer dilution method. In the brain, the reference molecule was an intravascular marker (Crone's method) whereas inthe salivary gland the reference was an extracellular marker of similar size to the test molecule. The unidirectional flux was related to a maximal uptake, U: U = 1 --test concentration/reference concentration Uptake and cross-inhibition experiments in brain suggest the presence of only a long-chain neutral L-amino acid transport system (leucine, phenyl-alanine, tryptophan, tyrosine, valine, methionine). In contrast, results in the salivary gland suggest 4 transport systems: 1. large neutral, 2. small neutral (alanine, serine), 3. basic (lysine) and 4. acidic (aspartic, glutamic). The same method was applied to localize binding sites. Ouabain bound very significantly to the salivary epithelium but not at all to the brain endothelium. The method described is of interest since it can be extended to any organ and possibly to man.
采用无损、首次循环、双示踪剂稀释法，比较了脑毛细血管内皮细胞腔面和唾液腺上皮细胞基底侧的氨基酸转运情况。在脑中，参考分子是一种血管内标记物（克隆方法），而在唾液腺中，参考物是一种与测试分子大小相似的细胞外标记物。单向通量与最大摄取量U相关：U = 1 - 测试浓度/参考浓度。脑中的摄取和交叉抑制实验表明，仅存在一种长链中性L-氨基酸转运系统（亮氨酸、苯丙氨酸、色氨酸、酪氨酸、缬氨酸、蛋氨酸）。相比之下，唾液腺中的结果表明存在4种转运系统：1. 大中性氨基酸转运系统，2. 小中性氨基酸转运系统（丙氨酸、丝氨酸），3. 碱性氨基酸转运系统（赖氨酸）和4. 酸性氨基酸转运系统（天冬氨酸、谷氨酸）。同样的方法被用于定位结合位点。哇巴因与唾液腺上皮细胞有非常显著的结合，但与脑内皮细胞完全不结合。所描述的方法很有意义，因为它可以扩展到任何器官，甚至可能应用于人类。
