Activation of NMDA receptors linked to modulation of voltage-gated ion channels and functional implications
Activation of NMDA receptors linked to modulation of voltage-gated ion channels and functional implications
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DOI：
10.1152/ajpcell.00252.2002
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发表时间：
2003-03-01
影响因子：
5.5
通讯作者：
Linn, CL
中科院分区：
文献类型：
--
作者：
Davis, SF;Linn, CL
鲶鱼（Ictalurus punctatus）视锥水平细胞含有N-甲基-D-天冬氨酸（NMDA）受体，其功能尚未确定。在本研究中，我们研究了NMDA受体激活对电压门控离子通道活性的影响。NMDA受体激活产生了长期的电压门控钠和钙电流的下调，但对延迟整流钾电流没有影响。在AP-7的存在下，NMDA的作用被消除。为了确定NMDA受体激活是否具有功能性影响，将分离的鲶鱼视锥水平细胞电流钳位以模拟细胞的生理反应。当水平细胞去极化时，它们引起单个去极化过冲，并维持去极化稳态膜电位。NMDA可降低去极化超调的幅度，增加去极化稳态膜电位。在AP-7的存在下，NMDA的两种作用都被消除。这些结果支持这一假设，激活的NMDA受体在鲶鱼水平细胞可能会影响通过远端视网膜传递的视觉信息的类型。
Catfish (Ictalurus punctatus) cone horizontal cells contain N-methyl-D-aspartate (NMDA) receptors, the function of which has yet to be determined. In the present study, we have examined the effect of NMDA receptor activation on voltage-gated ion channel activity. NMDA receptor activation produced a long-term downregulation of voltage-gated sodium and calcium currents but had no effect on the delayed rectifying potassium current. NMDA's effect was eliminated in the presence of AP-7. To determine whether NMDA receptor activation had functional implications, isolated catfish cone horizontal cells were current clamped to mimic the cell's physiological response. When horizontal cells were depolarized, they elicited a single depolarizing overshoot and maintained a depolarized steady state membrane potential. NMDA reduced the amplitude of the depolarizing overshoot and increased the depolarized steady-state membrane potential. Both effects of NMDA were eliminated in the presence of AP-7. These results support the hypothesis that activation of NMDA receptors in catfish horizontal cells may affect the type of visual information conveyed through the distal retina.