Patch-clamp studies of glutamate receptor channels in cultured hippocampal neurons.

谷氨酸是哺乳动物中枢神经系统中介导兴奋性突触传递的主要神经递质。此外，越来越多的证据表明，由谷氨酸引起的细胞事件在诱导突触传递功效的可塑性变化中起关键作用。因此，阐明谷氨酸及其相关兴奋性氨基酸（EAAS）对中枢神经元膜特性的影响具有重要意义。在这项研究中，我们研究了EAAs激活的受体通道的特性在培养的大鼠海马神经元。膜片钳技术的全细胞和外向配置被用来研究宏观和单通道电流。主要研究结果如下：1.透过谷氨酸受体通道的离子有Na^+、K^+和Ca^2+.谷氨酸激活几种不同水平的单通道事件，单通道电导为40-50 pS和< 20 pS。的 ...更多信息 大（40-50 pS）和小（< 20 pS）事件分别是由于N-甲基-D-天冬氨酸（NMDA）和非NMDA（使君子酸或红藻氨酸）受体的激活。细胞<21>外液中Mg ~（2+）在-40 mV以上的电位范围内显著抑制NMDA通道的开放。NMDA受体通道对Ca^&lt;2+&gt;具有高度通透性。根据恒场方程计算P_<ca>/P_<na>= 6.2。NMDA通道在二价阳离子中的渗透性顺序为Ba^&lt;2+&gt;（1.2）&gt; Ca^&lt;2+&gt;（1.0）&gt; Sr^&lt;2+&gt;（0.8）&gt; Mn^&lt;2+&gt;（0.3）&gt;&gt; Mg^&lt;2+&gt;（&lt;0.02）。喹啉酸是一种兴奋性毒性脑代谢物，选择性激活NMDA受体通道。红藻氨酸受体通道分为两类。1型受体的Ca^2+渗透性非常低.相反，2型受体对Ca^&lt;2+&gt;的通透性相对较高（P_<ca>/P_<na>=2.3）。需要研究来表征2型红藻氨酸受体的单通道特性。少

It is widely accepted that glutamate is the principal neurotransmitter that mediates excitatory synaptic transmission in the mammalian central nervous system. Furthermore, evidence is accumulating that cellular events caused by glutamate play a key role in the induction of plastic changes in the efficacy of the synaptic transmission. Therefore it is important to clarify changes in the membrane properties induced by glutamate and related excitatory amino acids (EAAS) in the central neurons. In this study, we examined the properties of receptor channels activated by EAAs in cultured rat hippocampal neurons. The whole-cell and outside-out configurations of the patch-clamp technique were used to study macroscopic and single-channel currents. The results are summarized as follows:1. The ions permeant through glutamate receptor channels are Na^+, K^+ and Ca^<2+>.2. Glutamate activated single channel events of several different levels with single-channel conductances 40-50 pS and < 20 pS. The … More large (40-50 pS) and small (< 20 pS) events were due to the activation of N-methyl-D-aspartate (NMDA) and non-NMDA (quisqualate, or kainate) receptors, respectively.3. Mg^<21> in the extracellular solution markedly suppressed the opening of NMDA channels in the potential range more negative than -40 mV.4. The NMDA receptor channel was highly permeable to Ca^<2+>. The value Of P_<ca>/P_<na> was 6.2 according to the constant field equation. The permsability sequence of the NMDA channel among the divalent cations was determined to be Ba^<2+>(1.2) > Ca^<2+>(1.0) > Sr^<2+>(0.8) > Mn^<2+>(O.3)>> Mg^<2+>(<O.02).5. Quinolinate, an excitotoxic brain metabolite, selectively activated NMDA receptor channels.6. Kainate receptor channels were classified into two types. The Ca^<2+> permeability of the type 1 receptor was very low. In contrast, the type 2 receptor showed relatively high permeability to Ca^<2+> (P_<ca>/P_<na>=2.3). Study is needed to characterize single-channel properties of the type 2 kainate receptor. Less