Moore L E, Buchanan J T, Murphey C R
Equipe de Neurobiologie, C.N.R.S., University of Rennes I, France.
Biophys J. 1995 Jan;68(1):96-103. doi: 10.1016/S0006-3495(95)80163-3.
Small volumes of N-Methyl-D-Aspartate (NMDA) and non-NMDA excitatory amino acid receptor agonists were applied to localized regions of the dendritic trees of lamprey spinal neurons along their medial-lateral axis to obtain a spatial map of glutamate receptor distribution. Voltage clamp and frequency domain methods were used to obtain quantitative kinetic data of the voltage dependent ionic channels located both on the soma and on highly branched dendritic membranes. Pressure pulses of NMDA applied to the most peripheral regions of the dendritic tree elicited large somatic impedance increases, indicating that the most peripheral dendrites are well supplied with NMDA receptors. Experiments done with kainate did not elicit somatic responses to agonist applications on peripheral dendrites. The data obtained are consistent with the hypothesis that the activation of NMDA receptors by exogenous glutamate is significantly modified by the simultaneous activation of non-NMDA receptors, which shunts the NMDA response. The non-NMDA shunting hypothesis was tested by a combined application of kainate and NMDA to mimic the action of glutamate showing that the shunting effect of non-NMDA receptor activation virtually abolished the marked voltage dependency typical of NMDA receptor activation. These data were interpreted with a compartmental neuronal model having both NMDA and non-NMDA receptors.
将小剂量的N-甲基-D-天冬氨酸（NMDA）和非NMDA兴奋性氨基酸受体激动剂沿着七鳃鳗脊髓神经元树突的中轴-侧轴应用于其树突树的局部区域，以获得谷氨酸受体分布的空间图谱。使用电压钳和频域方法来获取位于胞体和高度分支的树突膜上的电压依赖性离子通道的定量动力学数据。将NMDA压力脉冲施加到树突树的最外围区域会引起胞体阻抗大幅增加，这表明最外围的树突富含NMDA受体。用红藻氨酸进行的实验未引发对外周树突上激动剂应用的胞体反应。所获得的数据与以下假设一致，即外源性谷氨酸对NMDA受体的激活会因非NMDA受体的同时激活而显著改变，后者会分流NMDA反应。通过联合应用红藻氨酸和NMDA来模拟谷氨酸的作用，对非NMDA分流假设进行了测试，结果表明非NMDA受体激活的分流效应实际上消除了NMDA受体激活典型的显著电压依赖性。这些数据用具有NMDA和非NMDA受体的神经元房室模型进行了解释。
