Facilitated transport of L-phenylalanine across blood-nerve barrier of rat peripheral nerve.
Facilitated transport of L-phenylalanine across blood-nerve barrier of rat peripheral nerve.
复制标题
促进 L-苯丙氨酸穿过大鼠周围神经的血神经屏障的转运。
DOI：
10.1152/ajpregu.1990.258.6.r1436
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发表时间：
1990
影响因子：
--
通讯作者：
S. Rapoport
中科院分区：
文献类型：
--
作者：
K. C. Wadhwani;Q. Smith;S. Rapoport
通过将含有痕量L-[14 C]苯丙氨酸和[3 H]葡聚糖（血管标记物）的林格溶液灌注通过麻醉大鼠的后肢，研究了L-苯丙氨酸穿过血液-神经屏障的转运。在灌注结束时，取出一段坐骨神经，冷冻，脱鞘，并进行放射性计数。血-神经屏障（PABNB）对L-[14 C]苯丙氨酸的渗透性-表面积乘积从58 +/- 9 X 10（-5）降至1.7 +/- 0.3 X 10（-5）（SE）ml·s-1·g湿重-1，当灌流液中未标记的L-苯丙氨酸浓度增加到10 mM时，D-苯丙氨酸对L-[14 C]的抑制作用较小。苯丙氨酸摄取量高于L-苯丙氨酸。PABNB在灌注介质中存在50 mM α-（甲氨基）异丁酸（MeAIB）时没有变化，也没有通过用Tris. HCl代替NaCl而变化。然而，加入50 mM 2-氨基二环（2，2，1）庚烷-2-羧酸（BCH）使PABNB减少至2.1 +/- 0.3 X 10（-5）ml.s-1. g湿重-1（n = 4）。通过原位孵育测定的L-[14 C]苯丙氨酸在神经外膜屏障处的PA（PAper）为1.4 +/- 0.2 X 10（-5）ml.s-1.g湿重-1（n = 6），并且不受孵育培养基中10 mM L-苯丙氨酸浓度的影响。结果首次证明L-苯丙氨酸在大鼠外周神经的血神经屏障上存在载体介导的转运系统。
L-Phenylalanine transport across the blood-nerve barrier was studied by perfusing Ringer solution containing trace amounts of L-[14C]phenylalanine and [3H]dextran (a vascular marker) through the hindlimb of an anesthetized rat. At the end of perfusion, a segment of sciatic nerve was removed, frozen, desheathed, and processed for radioactivity counting. The permeability-surface area product of the blood-nerve barrier (PABNB) to L-[14C]phenylalanine decreased from 58 +/- 9 X 10(-5) to 1.7 +/- 0.3 X 10(-5) (SE) ml.s-1.g wet wt-1, as the perfusate concentration of unlabeled L-phenylalanine was increased to 10 mM. D-Phenylalanine had less of an inhibitory effect on L-[14C]phenylalanine uptake than did L-phenylalanine. PABNB did not change in the presence of 50 mM alpha-(methylamino)isobutyric acid (MeAIB) in the perfusion medium, nor by replacing NaCl by Tris.HCl. However, addition of 50 mM 2-aminobicyclo(2,2,1)heptane-2-carboxylic acid (BCH) reduced PABNB to 2.1 +/- 0.3 X 10(-5) ml.s-1.g wet wt-1 (n = 4). PA at epiperineurial barrier (PAper) of L-[14C]phenylalanine at the epiperineurial barrier, determined from in situ incubation, was 1.4 +/- 0.2 X 10(-5) ml.s-1.g wet wt-1 (n = 6) and was unaffected by 10 mM L-phenylalanine concentration in the incubation medium. The results demonstrate for the first time carrier-mediated transport system for L-phenylalanine at the blood-nerve barrier of the rat peripheral nerve.