Finger W, Martin C
Physiologisches Institut der Technischen Universität München, Munich, F.R.G.
Neurosci Lett. 1989 Feb 13;97(1-2):129-34. doi: 10.1016/0304-3940(89)90151-1.
Experiments were carried out in voltage-clamped fibres of the opener muscle of the first walking leg or claw of small crayfish. Repetitive discharges in the inhibitory nerve innervating the muscle were induced by adding serotonin (10(-6) mol/l) and forskolin (10(-4) mol/l) to the superfusate. Rates of nerve discharge were determined by recording nerve evoked inhibitory postsynaptic currents (IPSCs) in the voltage-clamped muscle fibre. Subsequently, the effect of gamma-aminobutyric acid (GABA) on the rate of IPSCs in normal and Cl- -deficient superfusate was investigated. In normal superfusate GABA (10(-5) mol/l) abolished the IPSCs whereas in Cl- -deficient superfusate GABA (10(-4) mol/l) enhanced the rate of IPSCs. Moreover, in Cl- -deficient superfusate the rate of asynchronous quantal release of inhibitory transmitter could be enhanced by GABA. The results indicate that in the crayfish neuromuscular junction the inhibitory axon is supplied with GABA receptors which may affect (a) axonal excitation and (b) quantal output at the inhibitory axon terminals.
实验是在小型小龙虾第一步行足或螯的开肌的电压钳制纤维上进行的。通过向灌流液中添加5-羟色胺（10⁻⁶mol/L）和福斯可林（10⁻⁴mol/L）来诱导支配该肌肉的抑制性神经产生重复放电。通过记录电压钳制的肌纤维中神经诱发的抑制性突触后电流（IPSCs）来测定神经放电速率。随后，研究了γ-氨基丁酸（GABA）对正常灌流液和缺乏氯离子的灌流液中IPSCs速率的影响。在正常灌流液中，GABA（10⁻⁵mol/L）可消除IPSCs，而在缺乏氯离子的灌流液中，GABA（10⁻⁴mol/L）可提高IPSCs的速率。此外，在缺乏氯离子的灌流液中，GABA可增强抑制性递质的异步量子释放速率。结果表明，在小龙虾神经肌肉接头处，抑制性轴突配备有GABA受体，这些受体可能会影响（a）轴突兴奋和（b）抑制性轴突末梢的量子输出。
