The effect of glutamate and N-methyl-d-aspartate (NMDA) on electrical signalling – action potentials (AP) and excitation current transients – was studied in intact macrophyte Nitellopsis obtusa (Characeaen) internodal cell. Intracellular glass electrode recordings of single cell in current clamp and two-electrode voltage clamp modes indicate that glutamate (Glu, 0.1–1.0 mM) and NMDA (0.01–1.0 mM) increase electrically induced AP amplitude by hyperpolarising excitation threshold potential (E_th) and prolong AP fast repolarisation phase. Amplitude of Cl^– current transient, as well as its activation and inactivation durations were also increased. Both Glu and NMDA act in a dose-dependent manner. The effect of NMDA exceeds that of Glu. Ionotropic glutamate receptor inhibitors AP-5 (NMDA-type receptors) and DNQX (AMPA/Kainate-type) have no effect on Nitellopsis cell electrical signalling per se, yet robustly inhibit excitatory effect of NMDA. This study reinforces NMDA as an active component in glutamatergic signalling at least in some plants and stresses the elaborate fine-tuning of electrical signalling.

研究了谷氨酸和N-甲基-d-天门冬氨酸（NMDA）对完整的大型植物扁桃体（Characeaen）间节细胞中电信号传导（动作电位（AP）和激发电流瞬变）的影响。电流钳和两电极电压钳模式下单细胞的细胞内玻璃电极记录表明，谷氨酸（Glu，0.1–1.0 mM）和NMDA（0.01–1.0 mM）通过超极化激发阈值电势（E _th）来增加电感应AP幅度。并延长AP快速复极化阶段。Cl的幅度^–当前的瞬态及其激活和灭活的持续时间也增加了。Glu和NMDA均以剂量依赖性方式起作用。NMDA的作用超过了Glu。离子型谷氨酸受体抑制剂AP-5（NMDA型受体）和DNQX（AMPA / Kainate型）对烟蝇细胞的电信号传导本身没有影响，但能强烈抑制NMDA的兴奋作用。这项研究至少在某些植物中增强了NMDA作为谷氨酸能信号传导中的活性成分，并强调了电信号传导的精细微调。