γ-氨基丁酸对小龙虾牵张感受器的作用时程：γ-氨基丁酸可饱和摄取的证据。

The time course of GABA action on the crayfish stretch receptor: evidence for a saturable GABA uptake.

作者信息

Deisz R A, Dose M, Lux H D

出版信息

Neurosci Lett. 1984 Jun 29;47(3):245-50. doi: 10.1016/0304-3940(84)90521-4.

Abstract

The conductance increase induced by bath application of GABA has been measured in voltage-clamped stretch-receptor neurones of crayfish. A rapid conductance increase was obtained only at GABA concentrations above 3.3 X 10(-4) M. The response to lower GABA concentrations (between 10(-4) and 10(-6) M) developed slowly over 30-60 min. Repetitive application of intermediate GABA concentrations induced postsynaptic conductance changes which were progressively enhanced in their onset and magnitude. In the presence of nipecotic acid or in Na+-free Ringer solutions, the response to all GABA concentrations was rapid and constant for each concentration. The time course of inhibitory postsynaptic currents was unaffected by nipecotic acid. These results suggest the presence of a saturable GABA uptake system which limits the access of bath-applied GABA to postsynaptic receptors. This system has little if any effect on the termination of response to synaptically released GABA.

摘要

在电压钳制的小龙虾牵张感受器神经元中，已测量了通过浴灌加γ-氨基丁酸（GABA）所诱导的电导增加。仅在GABA浓度高于3.3×10⁻⁴M时，才获得快速的电导增加。对较低GABA浓度（10⁻⁴至10⁻⁶M之间）的反应在30 - 60分钟内缓慢发展。重复施加中等GABA浓度会诱导突触后电导变化，其起始和幅度会逐渐增强。在存在哌啶酸或无钠林格溶液的情况下，对所有GABA浓度的反应对于每种浓度都是快速且恒定的。抑制性突触后电流的时间进程不受哌啶酸影响。这些结果表明存在一个可饱和的GABA摄取系统，该系统限制了浴灌加的GABA与突触后受体的接触。该系统对突触释放的GABA反应的终止几乎没有影响。