Single-channel analyses of ethanol modulation of neuronal nicotinic acetylcholine receptors.
Single-channel analyses of ethanol modulation of neuronal nicotinic acetylcholine receptors.
复制标题
DOI：
10.1097/01.alc.0000125349.99823.8a
复制
发表时间：
2004-05
期刊：
影响因子：
--
通讯作者：
Yi Zuo;K. Nagata;J. Yeh;T. Narahashi
中科院分区：
文献类型：
--
作者：
Yi Zuo;K. Nagata;J. Yeh;T. Narahashi
背景我们以前曾报道乙醇可增强大鼠皮层神经元和人胚肾细胞中稳定表达的α 4 β 2神经元烟碱乙酰胆碱受体的乙酰胆碱诱导电流。高浓度乙酰胆碱诱发的最大电流增强表明乙醇影响通道门控。方法我们采用单通道膜片钳技术研究乙醇对人胚肾细胞α 4 β 2受体的影响。结果乙酰胆碱至少激活了40.5pS和21.9pS两个电导态。30 nM的乙酰胆碱主要诱导高电导态电流（占总数的85%）。乙醇不影响单通道电导，但选择性地调制高电导态电流。高电导态电流表现出两个开放时间常数。100 mM乙醇使两个时间常数分别从1.9 msec增加到2.8 msec和从9.0 msec增加到15.5 msec。乙醇也延长了突释持续时间和突释内的开放时间，增加了通道开放的概率。结论单通道参数的这些变化表明，乙醇稳定了开放状态的α 4 β 2受体通道，解释了乙醇如何进一步增强最大乙酰胆碱诱导的全细胞电流。
BACKGROUND We have previously reported that ethanol potentiates the acetylcholine-induced currents of the alpha4beta2 neuronal nicotinic acetylcholine receptors in rat cortical neurons and of those that are stably expressed in human embryonic kidney cells. The potentiation of the maximal currents evoked by high concentrations of acetylcholine suggests that ethanol affects the channel gating. METHODS We performed single-channel patch-clamp experiments to elucidate the detailed mechanism of ethanol modulation of the alpha4beta2 receptor that is stably expressed in human embryonic kidney cells. RESULTS At least two conductance states, 40.5 pS and 21.9 pS, were activated by acetylcholine. Acetylcholine at 30 nM predominantly induced the high conductance state currents (85% of total). Ethanol did not affect the single-channel conductance but selectively modulated the high-conductance state currents. The high-conductance state currents exhibited two open time constants. Both time constants were increased by 100 mM ethanol, from 1.9 msec to 2.8 msec and from 9.0 msec to 15.5 msec, respectively. Ethanol also prolonged the burst duration and the open time within burst and increased the probability of channel opening. CONCLUSIONS These changes in single-channel parameters indicate that ethanol stabilizes the alpha4beta2 receptor-channel in the opening state, explaining how the maximum acetylcholine-induced whole-cell currents are further potentiated by ethanol.