Slow deactivation kinetics of NMDA receptors containing NR1 and NR2D subunits in rat cerebellar Purkinje cells
Slow deactivation kinetics of NMDA receptors containing NR1 and NR2D subunits in rat cerebellar Purkinje cells
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DOI：
10.1111/j.1469-7793.2000.t01-1-00299.x
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发表时间：
2000-06-01
影响因子：
5.5
通讯作者：
Cull-Candy, SG
中科院分区：
文献类型：
--
作者：
Misra, C;Brickley, SG;Cull-Candy, SG
1.在幼年大鼠小脑片上，我们用膜片钳记录的方法研究了含有NR1和NR2D亚基的天然IV-甲基-D-天冬氨酸受体(NMDAR)的失活动力学。NMDAR介导的全细胞电流在20mU N-甲基-D-天冬氨酸和50 mU-M甘氨酸的作用下被激发。NMDAR介导的电流很小，平均全细胞电导约为750pS.在外向膜贴片上快速施加1 mM谷氨酸的短脉冲(1-10ms)后，我们观察到一种低电导型的单通道活动，在去掉激动剂后持续到30 S。对单个通道开口的分析显示，主导电态和副导电态之间的跃迁不对称--这是含有NR1/NR2D的NMDAR的特征。平均宏观电流呈现出一个衰减的时间过程，该过程可用时间常数类似于3S.5的单指数函数描述。我们得出结论，含有NR1/NR2D的天然NMDAR和它们的重组同行一样，表现出非常缓慢的失活动力学。这一特征应该为识别突触上的这些受体提供了一种手段，并表明它们对迄今所描述的突触NMDAR电流没有贡献。
1. We have examined the deactivation kinetics of native Iv-methyl-D-aspartate receptors (NMDARs) containing NR1 and NR2D subunits by patch-clamp recording from Purkinje cells in cerebellar slices from young rats.2. NMDAR-mediated whole-cell currents were elicited in response to bath application of 20 mu M NMDA and 50 mu M glycine. The NMDAR-mediated currents were small, with an average whole-cell conductance of approximately 750 pS.3. Following the rapid application of brief pulses (1-10 ms) of 1 mM glutamate to outside-out membrane patches, we observed a low-conductance type of single-channel activity which lasted up to 30 s after the removal of agonist.4. Analysis of individual channel openings revealed asymmetry of transitions between the main- and subconductance states - a characteristic of NR1/NR2D-containing NMDARs. The averaged macroscopic current exhibited a decay time course which was well described by a single exponential function with a time constant of similar to 3 s.5. We conclude that native NR1/NR2D-containing NMDARs, like their recombinant counterparts, display very slow deactivation kinetics. This feature should provide a means for identification of these receptors at synapses, and indicates that they do not contribute to the synaptic NMDAR currents so far described.