Kinetics of desensitization and recovery from desensitization for human α4β2-nicotinic acetylcholine receptors stably expressed in SH-EP1 cells
Kinetics of desensitization and recovery from desensitization for human α4β2-nicotinic acetylcholine receptors stably expressed in SH-EP1 cells
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DOI：
10.1038/aps.2009.48
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发表时间：
2009-06-01
影响因子：
8.2
通讯作者：
Lukas, Ronald J.
中科院分区：
文献类型：
--
作者：
Yu, Kewei D.;Liu, Qiang;Lukas, Ronald J.
目的：研究明确在 SH-EP1 人上皮细胞系中异源表达的人 α4β2-烟碱乙酰胆碱受体 (nAChR) 脱敏发生和恢复的动力学。方法：进行全细胞膜片钳记录以评估 α4β2-nAChR 电流。结果：应用 0.1 μmol/L 尼古丁或 1 mmol/L乙酰胆碱（ACh）1秒或更长时间诱导两个阶段，时间常数类似于70和700毫秒，用于α4β2-nAChR脱敏的开始。对于给定的激动剂暴露持续时间，尼古丁诱导的脱敏恢复速度慢于乙酰胆碱诱导的脱敏恢复。与已发表的报告的比较表明，α4β2-nAChR从脱敏中恢复的时间常数小于在相同浓度和暴露时间的激动剂下产生的人肌肉型nAChR([1])从脱敏中恢复的时间常数。此外，人类 α 4 β 2-nAChR 脱敏程度和恢复率是相同的，无论它们是使用全细胞记录测量还是基于使用同位素离子流测定的已发表研究结果([2])；这种等式证明了这些技术在评估 nAChR 脱敏方面具有同等的合法性。也许最重要的是，从脱敏中恢复也最适合双相过程。然而，无论是单指数还是双指数，随着脱敏脉冲期间激动剂暴露持续时间的增加，脱敏恢复的半衰期逐渐变长。结论：这些发现表明，在许多独特的脱敏状态中存在α4β2-nAChR，并且随着激动剂暴露持续时间的增加，逐渐诱导更深的脱敏状态。
Aim: Studies were conducted to define the kinetics of the onset of and recovery from desensitization for human alpha 4 beta 2-nicotinic acetylcholine receptors (nAChR) heterologously expressed in the SH-EP1 human epithelial cell line.Methods: Whole-cell patch clamp recordings were performed to evaluate alpha 4 beta 2-nAChR currents.Results: Application of 0.1 mu mol/L nicotine or 1 mmol/L acetylcholine (ACh) for 1 s or longer induced two phases, with time constants of similar to 70 and similar to 700 ms, for the onset of alpha 4 beta 2-nAChR desensitization. For a given duration of agonist exposure, recovery from desensitization induced by nicotine was slower than recovery from ACh-induced desensitization. Comparisons with published reports indicate that time constants for the recovery of alpha 4 beta 2-nAChRs from desensitization are smaller than those for the recovery of human muscle-type nAChRs([1]) from desensitization produced by the same concentrations and durations of exposure to an agonist. Moreover, the extent of human alpha 4 beta 2-nAChR desensitization and rate of recovery are the same, regardless of whether they are measured using whole-cell recording or based on published findings([2]) using isotopic ion flux assays; this equality demonstrates the equivalent legitimacy of these techniques in the evaluation of nAChR desensitization. Perhaps most significantly, recovery from desensitization also was best fit to a biphasic process. Regardless of whether it was fit to single or double exponentials, however, half-times for recovery from desensitization grew progressively longer with an increased duration of agonist exposure during the desensitizing pulse.Conclusion: These findings indicate the existence of alpha 4 beta 2-nAChRs in many distinctive states of desensitization, as well as the induction of progressively deeper states of desensitization with the increased duration of agonist exposure.