Actions of n‐alcohols on nicotinic acetylcholine receptor channels in cultured rat myotubes.
Actions of n‐alcohols on nicotinic acetylcholine receptor channels in cultured rat myotubes.
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正构醇对培养大鼠肌管烟碱乙酰胆碱受体通道的作用。
DOI：
10.1113/jphysiol.1991.sp018604
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
D. Haydon
中科院分区：
文献类型：
--
作者：
R. Murrell;M. Braun;D. Haydon
1.通过记录从培养的大鼠肌管分离的由内而外的膜膜片的单个ACh激活通道活性，研究了从戊醇到十二醇的正醇对烟碱乙酰胆碱受体（nAChR）通道的作用。将醇应用于膜的细胞质侧;水溶液浓度范围为11.7 mM-戊醇至0.02 mM-十二烷醇。2.中间链醇（戊醇到辛醇）导致通道电流在完全打开和关闭状态水平之间波动，使得打开发生在被短暂间隙中断的爆发中。闭合时间分布与两个指数分量拟合良好，快速分量代表爆发内的闭合。在一个突发的间隙的数量是依赖于酒精浓度，而间隙持续时间是独立的浓度，但随着链长度的增加的醇辛醇。3.壬醇和癸醇减少了开放爆发的平均持续时间，但并未导致爆发内短闭合间隔数量的增加。除了癸醇之外，正醇影响通道功能的能力下降。十一烷醇的饱和溶液（0.07 mM）使平均开放时间减少33 +/-17%，而十二烷醇的饱和溶液没有显著影响。4.戊醇和十一烷醇之间的所有正醇均降低了每次爆发的电流积分。IC 50如下：己醇，0.53 +/-0.14 mM;庚醇，0.097 +/-0.02 mM;辛醇，0.04 mM和壬醇，0.16 +/-0.035 mM。结果根据开放通道阻塞模型进行分析，阻塞状态之外还有长期的封闭阻塞状态。在检测的浓度范围内，这描述了所有正醇（C5至C12）对通道门控的影响。6.戊醇至壬醇的阻断速率常数（k+B）计算为2.8 - 5.7 X 10（6）M-1 S-1。这些值基于醇在其作用位点的浓度等于施加到膜上的水溶液浓度的假设。7.平衡解离常数（KD），从封闭和解除封闭速率常数（KD = k-B/k+B）计算，随着链长的增加而降低，从8 mM戊醇到0.15 mM辛醇。吸附到作用位点的每个亚甲基的标准自由能计算为约-3.3 kJ mol-1。（400字处截断摘要）
1. The actions of the n‐alcohols from pentanol to dodecanol on nicotinic acetylcholine receptor (nAChR) channels were investigated by recording single ACh‐activated channel activity from inside‐out membrane patches isolated from cultured rat myotubes. Alcohols were applied to the cytoplasmic side of the membrane; aqueous concentrations ranged from 11.7 mM‐pentanol to 0.02 mM‐dodecanol. 2. The intermediate‐chain alcohols (pentanol to octanol) caused channel currents to fluctuate between the fully open and closed state level so that openings occurred in bursts interrupted by brief gaps. Closed time distributions were fitted well with two exponential components, the fast component representing the closures within a burst. The number of gaps within a burst was dependent on alcohol concentration whereas gap duration was independent of concentration but increased with increasing chain length of the alcohol up to octanol. 3. Nonanol and decanol reduced the mean duration of bursts of openings but did not cause an increase in the number of short closed intervals within a burst. Beyond decanol there was a decline in the ability of the n‐alcohols to affect channel function. A saturated solution of undecanol (0.07 mM) reduced the mean open time by 33 +/‐ 17%, whereas a saturated solution of dodecanol had no significant effect. 4. The current integral per burst was reduced by all the n‐alcohols between pentanol and undecanol. The IC50S were as follows: hexanol, 0.53 +/‐ 0.14 mM; heptanol, 0.097 +/‐ 0.02 mM; octanol, 0.04 mM and nonanol, 0.16 +/‐ 0.035 mM. 5. The results were analysed in terms of an open channel block model with a long‐lived closed‐blocked state beyond the blocked state. Over the range of concentrations tested this describes the effects of all the n‐alcohols (C5 to C12) on channel gating reasonably well. 6. Blocking rate constants (k+B) for pentanol through to nonanol were calculated to be between 2.8 and 5.7 X 10(6) M‐1 S‐1. These values are based on the assumption that the concentration of the alcohols at their site(s) of action was equal to the aqueous concentration applied to the membrane. 7. Equilibrium dissociation constants (KD), calculated from the blocking and unblocking rate constants (KD = k‐B/k+B), decreased with increasing chain length from 8 mM for pentanol to 0.15 mM for octanol. The standard free energy per methylene group for adsorption to the site of action was calculated to be about ‐3.3 kJ mol‐1.(ABSTRACT TRUNCATED AT 400 WORDS)