Identification and selective inhibition of the channel mode of the neuronal GABA transporter 1
Identification and selective inhibition of the channel mode of the neuronal GABA transporter 1
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DOI：
10.1124/mol.105.013870
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发表时间：
2005-12-01
影响因子：
3.6
通讯作者：
Schwarz, W
中科院分区：
文献类型：
--
作者：
Krause, S;Schwarz, W
抑制性神经递质GABA的转运蛋白GAT 1的功能通过在非洲爪蟾卵母细胞中的表达以及在电压钳条件下测量GABA诱导的[（3）H] GABA、（22）Na（+）和（36）Cl（-）摄取和GABA诱发的电流来表征。N-[4，4-二苯基-3-丁烯基]哌啶甲酸（SKF-89976-A）是GAT 1的特异性抑制剂，在我们的系统中用作药理学工具。GABA诱发电流可分解为与GABA摄取偶联的转运电流和与GABA摄取不偶联的发射门控电流。运输电流的结果，从一个固定的化学计量1 GABA/2 Na（+）/1 Cl（-）在每个周期期间运输，由放射性示踪剂通量测量。通过Na（+）-传导途径介导该递质门控电流。作为GABA摄取的竞争性抑制剂，SKF-89976-A可以分离两种电流成分。GABA的摄取被阻断的KI值约为7 μ M，而未偶联的发射门控电流被抑制的KI值约为0.03 μ M。因此，本研究的结果不仅确定了GAT 1的运输模式和通道模式，而且还提出了在生理环境中分离这些组分的可能性。
The function of GAT1, the transporter for the inhibitory neurotransmitter GABA, is characterized by expression in Xenopus laevis oocytes and measurements of GABA-induced uptake of [(3)H] GABA, (22)Na(+), and (36)Cl(-), and GABA-evoked currents under voltage-clamp conditions. N-[4,4-Diphenyl-3-butenyl]nipecotic acid (SKF-89976-A), a specific inhibitor of GAT1, is used in our system as a pharmacological tool. The GABA-evoked current can be decomposed into a transport current, which is coupled to the GABA uptake, and a transmitter-gated current, which is uncoupled from the GABA uptake. The transport current results from a fixed stoichiometry of 1 GABA/2 Na(+)/1 Cl(-) transported during each cycle, as determined by radioactive tracer flux measurements. The transmitter-gated current is mediated by an Na(+) -conductance pathway. As a competitive inhibitor for GABA uptake, SKF-89976-A can separate the two current components. The GABA uptake is blocked with a K I value of approximately 7 mu M, whereas the uncoupled transmitter-gated current is inhibited with a K I value of approximately 0.03 mu M. Thus, the results of this study not only identify the transport mode and the channel mode of GAT1 but also raise the possibility of separating these components in a physiological environment.