Glutamate and N-methyl-D-aspartate affect release from crayfish axon terminals in a voltage-dependent manner.
Glutamate and N-methyl-D-aspartate affect release from crayfish axon terminals in a voltage-dependent manner.
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谷氨酸和 N-甲基-D-天冬氨酸以电压依赖性方式影响小龙虾轴突末端的释放。
DOI：
10.1073/pnas.91.24.11586
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发表时间：
1994
影响因子：
11.1
通讯作者：
B. Yudelevitch
中科院分区：
文献类型：
--
作者：
H. Parnas;I. Parnas;R. Ravin;B. Yudelevitch
在小龙虾的神经肌肉接头中，兴奋性递质是谷氨酸。本研究表明，谷氨酸浓度低至5×10~(-7)M时，可影响去极化诱发的神经递质释放。此外，谷氨酸对释放的影响是电压依赖的，并且依赖于去极化脉冲的水平。神经末梢暴露于5×10(-7)M河豚毒素，然后用大片电极进行不同程度的去极化。根据去极化脉冲的幅度不同，谷氨酸(5×10(-7)至1×10(-5)M)对释放具有双重影响。在小的去极化脉冲下，谷氨酸减少了释放，而在大的去极化脉冲下，它增强了谷氨酸的释放。10(-6)M的谷氨酸对动作电位诱导的释放无明显影响。当谷氨酸浓度为10(-4)M时，动作电位引起的释放始终受到抑制。N-甲基-D-天冬氨酸模拟谷氨酸的作用之一：N-甲基-D-天冬氨酸(10(-7)~10(-5)M)在较小的去极化脉冲下减少释放，但在较大的去极化脉冲下不起作用。2-氨基-5-磷酸丙戊酸可阻断N-甲基-D-天冬氨酸的作用。
In the crayfish neuromuscular junction, the excitatory transmitter is glutamate. The present study shows that at concentrations as low as 5 x 10(-7) M, glutamate affects the depolarization-evoked release of neurotransmitter. Furthermore, the effect of glutamate on release is voltage-dependent and depends on the level of the depolarizing pulse. Nerve terminals were exposed to 5 x 10(-7) M tetrodotoxin and then depolarized to different levels by a macropatch electrode. Depending on the amplitude of the depolarizing pulse, glutamate (5 x 10(-7) to 1 x 10(-5) M) had a dual effect on release. At small depolarizing pulses, glutamate reduced release, whereas at large depolarizing pulses, it enhanced it. Glutamate at 10(-6) M had no significant effect on action-potential-induced release. At 10(-4) M glutamate, the action-potential-induced release was always inhibited. N-Methyl-D-aspartate was found to mimic one of the effects of glutamate: N-methyl-D-aspartate (10(-7) to 10(-5) M) reduced release at small depolarizing pulses but had no effect with larger depolarizations. 2-Amino-5-phosphonovaleric acid blocked the effect of N-methyl-D-aspartate.