Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida, USA.
J Neurophysiol. 2011 Oct;106(4):1629-36. doi: 10.1152/jn.00403.2011. Epub 2011 Jul 13.
D-Aspartate (D-Asp) activates an excitatory current in neurons of Aplysia californica. Although D-Asp is presumed to activate a subset of L-glutamate (L-Glu) channels, the identities of putative d-Asp receptors and channels are unclear. Whole cell voltage- and current-clamp studies using primary cultures of Aplysia buccal S cluster (BSC) neurons were executed to characterize D-Asp-activated ion channels. Both D-Asp and L-Glu evoked currents with similar current-voltage relationships, amplitudes, and relatively slow time courses of activation and inactivation when agonists were pressure applied. D-Asp-induced currents, however, were faster and desensitized longer, requiring 40 s to return to full amplitude. Of cells exposed to both agonists, 25% had D-Asp- but not L-Glu-induced currents, suggesting a receptor for D-Asp that was independent of l-Glu receptors. D-Asp channels were permeable to Na(+) and K(+), but not Ca²⁺, and were vulnerable to voltage-dependent Mg²⁺ block similarly to vertebrate NMDA receptor (NMDAR) channels. d-Asp may activate both NMDARs and non-l-Glu receptors in the nervous system of Aplysia.
天冬氨酸（D-Asp）在加利福尼亚海兔的神经元中激活兴奋性电流。虽然 D-Asp 被认为可以激活一组 L-谷氨酸（L-Glu）通道，但假定的 D-Asp 受体和通道的身份尚不清楚。使用加利福尼亚海兔口腔 S 簇（BSC）神经元的原代培养物进行全细胞膜电压和电流钳研究，以表征 D-Asp 激活的离子通道。当激动剂加压时，D-Asp 和 L-Glu 均能引起具有相似电流-电压关系、幅度和相对较慢激活和失活时间过程的电流。然而，D-Asp 诱导的电流更快，脱敏时间更长，需要 40 秒才能恢复到全幅度。在暴露于两种激动剂的细胞中，有 25%的细胞具有 D-Asp 但没有 L-Glu 诱导的电流，这表明存在一种独立于 l-Glu 受体的 D-Asp 受体。D-Asp 通道对 Na(+)和 K(+)具有通透性，但对 Ca²⁺没有通透性，并且对电压依赖性 Mg²⁺阻断的敏感性类似于脊椎动物 NMDA 受体（NMDAR）通道。D-Asp 可能在加利福尼亚海兔的神经系统中激活 NMDAR 和非 l-Glu 受体。
