Net uptake of aspartate by a high-affinity rat cortical synaptosomal transport system
Net uptake of aspartate by a high-affinity rat cortical synaptosomal transport system
复制标题
高亲和力大鼠皮质突触体转运系统对天冬氨酸的净摄取
DOI：
10.1016/0006-8993(79)90602-4
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发表时间：
1979
期刊：
影响因子：
2.9
通讯作者：
R. Roskoski
中科院分区：
文献类型：
--
作者：
R. Roskoski
高亲和转运系统（Km≈10 μM）对神经活性氨基酸的再摄取被认为终止了这些物质的作用。由于同质交换可能使摄取实验的解释复杂化，因此有必要在摄取之前证明神经活性氨基酸的净向内运输可以被认为是递质失活的可能机制。当大鼠皮质突触体与10 μM[14C]l-天冬氨酸孵育时，突触体组分的净（化学）和表观（放射性）摄取是相等的。虽然有净的天冬氨酸摄取到突触体部分，但在各种情况下可以证明天冬氨酸交换。净吸收表现出高亲和输运系统的特征，包括Na+和温度依赖。此外，净吸收需要KCl (orRbCl) - 1mM，但不需要放射性或表观吸收。LiCl, NH4Cl， CsCl和氯化胆碱不能支持净吸收。瓦巴因（0.1mM）抑制净吸收的程度大于表观吸收。虽然谷氨酸抑制天冬氨酸的摄取（反之亦然），但联合使用的净摄取大于单独使用。高亲和系统对天冬氨酸的净吸收与该系统可能在突触区失活中起作用的观点是一致的。
Reuptake of neuroactive amino acids by high affinity transport systems (Km≈ 10 μM) is thought to terminate the action of these substances. Since homoexchange can complicate the interpretation of uptake experiments, it is necessary to demonstrate net inward transport of neuroactive amino acids before uptake can be considered as a likely mechanism for transmitter inactivation. When rat cortical synaptosomes are incubated with 10 μM[14C]l-aspartate, net (chemical) and apparent (radioactive) uptake into the synaptosomal fractions are equivalent. Although there is net aspartate uptake into the synaptosome fraction, aspartate exchange can be demonstrated in a variety of conditions. Net uptake exhibits the characteristics of high-affinity transport systems including Na+- and temperature-dependence. Furthermore, KCl (orRbCl) — 1mM— are required for net uptake but not radioactive or apparent uptake. LiCl, NH4Cl, CsCl, and choline chloride fail to support net uptake. Ouabain (0.1mM) inhibits net uptake to a greater extent than apparent uptake. Although glutamate inhibits aspartate uptake (and vice versa), the net uptake of the combination is greater than that of each alone. The demonstration of net uptake of aspartate by a high-affinity system is consonant with the idea that this system may play a role in its inactivation in the synaptic region.