Nonstationary Noise Analysis of Membrane Currents
Nonstationary Noise Analysis of Membrane Currents
复制标题
膜电流的非平稳噪声分析
DOI：
10.1007/978-1-4684-4850-4_2
复制
发表时间：
1984
影响因子：
4.8
通讯作者：
F. Sigworth
中科院分区：
文献类型：
--
作者：
F. Sigworth
研究离子通道膜电流波动的最简单方法是将通道置于稳定的、部分激活的状态，并监测电流在其稳定平均值附近的波动。在实践中，由于通道本身的特性，这种实验通常是不可能的。例如，乙酰胆碱受体通道表现出脱敏过程，其中激动剂诱导的膜电流随时间下降。一些电压激活的通道表现出类似的行为：在稳定去极化期间，Na+通道自发失活。膜电流随时间的变化给噪声分析带来了实际和理论问题。由于波动的大小通常仅为平均电流的百分之几，因此每当发生小的基线漂移时就会出现严重的实际问题，因为漂移会严重污染根据波动计算的功率谱（图1）。在许多实验情况下，可以估计基线漂移并将其从记录中删除；然而，仍然存在一个理论问题：当平均电流本身随时间变化时，如何解释波动？
The simplest way to study membrane current fluctuations from ionic channels would be to place the channels into a steady, partly activated state and to monitor the fluctuations in the current around its steady mean value. In practice, an experiment of this kind is often not possible because of properties of the channels themselves. Acetylcholine-receptor channels, for example, show a desensitization process in which the agonist-induced membrane current declines with time. Some voltage-activated channels show a similar kind of behavior: during a steady depolarization, Na+ channels spontaneously inactivate. These changes in membrane current with time pose both practical and theoretical problems for noise analysis. Since the size of the fluctuations is typically only a few percent of the mean current, a serious practical problem arises whenever a small baseline drift occurs, since drift can seriously contaminate a power spectrum computed from the fluctuations (Fig. 1). In many experimental situations the baseline drift can be estimated and removed from the records; however a theoretical problem still remains: how should the fluctuations be interpreted when the mean current itself changes with time?