Ethanol potentiation of calcium-activated potassium channels reconstituted into planar lipid bilayers
Ethanol potentiation of calcium-activated potassium channels reconstituted into planar lipid bilayers
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DOI：
10.1124/mol.54.2.397
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发表时间：
1998-08-01
影响因子：
3.6
通讯作者：
Treistman, SN
中科院分区：
文献类型：
--
作者：
Chu, BS;Dopico, AM;Treistman, SN
我们研究了乙醇对从骨骼肌T-小管膜分离的大电导Ca 2+激活的K+（BK）通道的单通道特性的作用，并将其纳入平面脂质双层膜。我们利用这种制备，因为它缺乏细胞复杂性的大多数元素，包括细胞质成分和复杂的膜脂质组成和结构，以检查酒精作用的最低要求。临床相关浓度（25-200 mM）的乙醇增加了BK通道的活性，BK通道被整合到由磷脂酰乙醇胺（PE）单独或PE和磷脂酰丝氨酸组成的双层中。乙醇增强通道活性主要是由于关闭状态下平均花费的时间减少。乙醇没有显着影响BK通道的电流幅值-电压关系，表明K+通道电导不受药物的影响。虽然BK通道纳入仅由PE组成的双层的基线特性不同于PE/磷脂酰丝氨酸中的通道，预期从双层电荷的变化的方式，乙醇对通道活性的作用是定性相似的不同的脂质环境。乙醇对BK通道在平面双层的单通道特性的影响是非常相似的那些报道的乙醇对神经垂体BK通道的作用研究在天然膜，并克隆BK通道表达非洲爪蟾卵母细胞，这表明乙醇的网站和机制的行动被保存在这个大大简化的准备。
We examined the actions of ethanol on the single channel properties of large conductance Ca2+-activated K+ (BK) channels isolated from skeletal muscle T-tubule membranes and incorporated into planar lipid bilayer membranes. We have taken advantage of this preparation, because it lacks most elements of cellular complexity, including cytoplasmic constituents and complex membrane lipid composition and architecture, to examine the minimum requirements for the effects of alcohol. Clinically relevant concentrations (25-200 mM) of ethanol increased the activity of BK channels incorporated into bilayers composed of phosphatidylethanolamine (PE) alone or PE and phosphatidylserine. The potentiation of channel activity by ethanol was attributable predominantly to a decrease in the average amount of time spent in closed states. Ethanol did not significantly affect the current amplitude-voltage relationship for BK channels, indicating that channel conductance for K+ was unaffected by the drug. Although base-line characteristics of BK channels incorporated into bilayers composed only of PE differed from those of channels in PE/ phosphatidylserine in a manner expected from the change in bilayer charges, the actions of ethanol on channel activity were qualitatively similar in the different lipid environments. The effects of ethanol on single channel properties of BK channels in the planar bilayer are very similar to those reported for the action of ethanol on neurohypophysial BK channels studied in native membrane, and for cloned BK channels expressed in Xenopus laevis oocytes, which suggests that ethanol's site and mechanism of action are preserved in this greatly simplified preparation.