Kinetics of homomeric GluR6 glutamate receptor channels
Kinetics of homomeric GluR6 glutamate receptor channels
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DOI：
10.1016/s0006-3495(96)79375-x
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发表时间：
1996-10-01
影响因子：
3.4
通讯作者：
Dudel, J
中科院分区：
文献类型：
--
作者：
Heckmann, M;Bufler, J;Dudel, J
我们使用亚毫秒溶液交换系统研究了大鼠GluR6谷氨酸（glu）受体通道GluR6Q在外向补丁中的未编辑版本的动力学。与0.5 mM glu相似，通道激活达到半最大值。峰值电流对glu的双对数图的最大斜率近似于1.3，表明至少需要两个绑定步骤才能打开通道。电流在回答10毫米glu的脉冲上升时间短(10 - 90%的峰值电流)的类似于220亩年代类似于20度c上升时间增加而下降glu浓度,达到类似于6.0女士10μM glu, glu的继续存在,麻木的渠道,这脱敏可以用单时间常数描述类似7.0毫秒的脉冲glu 10毫米。10 mM glu长脉冲的稳态电流低于峰值电流的1/280；在30.0 ~ 0.3 mM glu范围内，脱敏时间常数与浓度无关，但浓度越低，脱敏时间常数越高。经过短暂的1毫秒的脉冲持续时间和10到0.3毫米glu,电流衰变时间常数的类似于2.5毫秒,复苏脱敏类似5 s的脉搏后,复苏的半场类似于2.2秒,连续应用低浓度的谷氨酸降低响应脉冲的峰值电流10毫米glu显著,连续观察响应减少百分之五十类似于0.3μM glu的存在。我们对同源GluR6的研究结果与小龙虾肌肉上完全脱敏的葡萄糖激活通道的周期性反应方案一致。
We studied the kinetics of the unedited version of rat GluR6 glutamate (glu) receptor channels, GluR6Q, in outside-out patches using a system for submillisecond solution exchange. Half-maximum activation of the channels was reached with similar to 0.5 mM glu. The maximum slope of the double-logarithmic plot of the peak current versus glu was similar to 1.3, indicating that at least two binding steps are necessary to open the channels. Currents in response to a pulse of 10 mM glu had a short rise time (10-90% of peak current) of similar to 220 mu s at similar to 20 degrees C. The rise time increased with falling glu concentration, reaching similar to 6.0 ms with 10 mu M glu, In the continued presence of glu, the channels desensitized, and this desensitization can be described with a single time constant of similar to 7.0 ms for a pulse of 10 mM glu. The steady-state current in response to a long pulse of 10 mM glu was below 1/280th of the peak current, The time constant of desensitization was found to be independent of concentration between 30.0 and 0.3 mM glu, but to be increased for lower concentrations. After a short pulse of 1 ms duration and 10 or 0.3 mM glu, currents decayed with a time constant of similar to 2.5 ms, Recovery from desensitization after a pulse took similar to 5 s, and the half-time of recovery was similar to 2.2 s, Continuous application of low concentrations of glutamate reduced the peak currents in response to a pulse of 10 mM glu markedly, Fifty percent response reduction was observed in the continuous presence of similar to 0.3 mu M glu. Our results for homomeric GluR6 agree with a cyclical reaction scheme developed for completely desensitizing, glu-activated channels on crayfish muscles.