VARIANCE AND SINGLE CHANNEL ANALYSIS OF ACH RECEPTORS

乙酰胆碱受体（AChR）通道存在于突触后 神经和肌肉细胞的膜。 这些通道将化学物质 乙酰胆碱（ACh）从突触前细胞释放到神经元的信号 突触后细胞的电去极化。 AChR通道具有 使用各种电生理生化和 形态学技术及其作用的分子机制， 开始被理解。 本文采用膜片钳技术， 检测单通道将用于研究门控机制， AChR频道 ACh对受体有两种作用：ACh打开通道，延长受体的作用时间。 暴露于乙酰胆碱会使受体脱敏。 初步实验已经 表明可以在膜片钳中区分这些动作 通过将ACh快速可逆地应用于切除的 从培养的肌肉细胞中分离出来的一小块膜。 三种实验 将在拟定研究中进行。 1)的激活 大量的通道通过ACh的重复应用。 非平稳 波动分析将用于计算明渠概率。 2)长时间应用ACh产生电流激活通道 放松 减敏的动力学将从这些推导出来 放松 3)AChR单通道的激活， 没有脱敏。 活化速率常数将由下式获得： 从单通道构造的开放时间和闭合时间直方图 记录 所有这些信息将用于构建动力学模型 通道激活和脱敏。 麻醉剂如酒精对脑功能的影响 还将研究AChR。 这些实验的结果将是 与麻醉剂相互作用模型的预测相比， 分子与受体蛋白的结合。 这种相互作用的影响 将考虑全身麻醉的机制。

Acetylcholine receptor (AChR) channels are found in the post-synaptic membranes of nerve and muscle cells. These channels translate the chemical signal of acetylcholine (ACh) release from the pre-synaptic cell into an electrical depolarization of the post-synaptic cell. AChR channels have been studied using a variety of electrophysiological biochemical and morphological techniques and the molecular mechanisms of its action are beginning to be understood. In this porposal, the patch clamp method of detecting single channels will be used to study the gating mechanisms of the AChR channel. ACh has two actions on the receptor: ACh opens the channel and prolonged exposures to ACh desensitize the receptor. Preliminary experiments have shown that it is possible to distinguish these actions in a patch clamp experiment by making rapid, reversible applications of ACh to an excised patch of membrane from cultured muscle cells. Three types of experiments will be performed in the proposed investigation. 1) The activation of large numbers of channels by repeated applications of ACh. Nonstationary fluctuation analysis will be used to calculate open channel probabilities. 2) The activation of channels by long applications of ACh produce current relaxations. The kinetics of desensitization will be deduced from these relaxations. 3) The activation of single AChR chanels under conditions of no desensitization. Activation rate constants will be obtained from open-and closed-time histograms constructed from the single channel records. All of this information will be used to construct a kinetic model of channel activation and desensitization. The effects of anesthetic agents such as alcohols on the function of the AChR will also be studied. The results of these experiments will be compared with the predictions of models for the interaction of anesthetic molecules with the receptor protein. The implications of such interactions for the mechanisms of general anesthesia will be considered.