EFFECTS OF ETHANOL ON RECEPTOR ION-CHANNEL BEHAVIOR

已经证明，乙醇降低表观解离 肌型烟碱离子通道激活常数 受体的 此外，已知乙醇加速了 受体的脱敏，这可能倾向于抵消 乙醇在某些情况下的增敏作用。 的 乙醇诱导的乙酰胆碱亲和力增加已经在 乙酰胆碱与受体结合及乙酰胆碱的研究 放射性离子的活化通量。 这一发现已被复制， 其他受体包括GABA受体和神经元乙酰胆碱 受体的 现在将在国家一级调查这一现象。 单个受体离子通道在培养细胞的膜片钳膜。 需要回答的问题是，乙醇诱导的 离子通量是由于通道开放速率的增加或 降低通道关闭的速率。 我们希望确定是否有 是在存在以下情况下通道打开的概率增加： 乙醇或如果通道仅仅在打开后保持打开更长时间。 同样，我们将研究乙醇对生物降解过程的影响。 通过施加不同浓度的激动剂脉冲的脱敏 到分离的膜斑，在那里受体的数量可以 通过电生理学方法定量， 可以估计由于脱敏引起的反应。 这种脱敏 也可以通过量化 受体引起的通道关闭时间分布 失活，因为它随着脱敏过程而变化。 这些 将用小鼠肌肉型乙酰胆碱进行研究， BC 3 H-1细胞上的神经乙酰胆碱受体，BC 3 H-1细胞上的大鼠神经乙酰胆碱受体， PC-12细胞和培养的小鼠脊髓神经元上的GABA受体。 准确理解乙醇在单一分子中的分子效应， 受体水平将有助于最终分析该网站是否 的作用是在脂质界面或受体蛋白。

It has been demonstrated that ethanol reduces the apparent dissociation constant for activation of the ion channel of the muscle-type nicotinic receptor. In addition it is known that ethanol accelerates the desensitization of the receptor which may tend to counteract the sensitizing effect of ethanol under some circumstances. The ethanol-induced increase in acetylcholine affinity has been verified in studies of acetylcholine binding to the receptor and acetylcholine activated flux of radioactive ions. This finding has been replicated for other receptors including the GABA receptor and a neuronal acetylcholine receptor. The phenomenon will now be investigated at the level of the single receptor ion channel in patch-clamped membranes of cultured cells. The question to be answered is whether the ethanol-induced increase in ion flux is due to an increase in the rate of channel opening or a decrease in the rate of channel closing. We wish to determine if there is an increase in the probability of channel opening in the presence of ethanol or if the channels merely stay open longer after opening. Similarly, we will study the effects of ethanol on the process of desensitization by applying pulses of agonist at different concentrations to isolated membrane patches where the number of receptors can be quantified by electrophysiological methods and the decay constant of the response due to desensitization can be estimated. This desensitization can also be related to the behavior of the single channel by quantifying the distribution of channel closed times which is caused by receptor inactivation as it changes with the desensitization process. These studies will be carried out with the mouse muscle-type acetylcholine receptor on BC3H-l cells, the rat neuronal acetylcholine receptor on PC-12 cells and the GABA receptor on cultured mouse spinal cord neurons. A precise understanding of the molecular effects of ethanol at the single receptor level will be useful in the final analysis of whether the site of action is at the lipid interface or the receptor protein.