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Hurst analysis applied to the study of single calcium-activated potassium channel kinetics

机译：Hurst分析应用于钙激活钾通道动力学的研究

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The gating of ion channels has been modeled by assuming that the transitions between open and closed states is a memoryless process. Nevertheless, analysis of records of unitary current events suggests that the kinetic process presents short-term memory, i.e. the open- and closed-dwell times are short-term correlated. Here the rescaled range analysis (RIS Hurst analysis) is used as a method to test long-term correlation, in single calcium-activated potassium channels present in Leydig cells. The Hurst coefficients, calculated for four different voltages (V) are: 0.634 +/- 0.022 (n = 3) for V = +20 mV; 0.635 +/- 0.012 (n = 4) for V = +40 mV; 0.606 +/- 0.020 (n = 4) for V = +60 mV and 0.608 +/- 0.026 (n = 4) for V = +80 mV. This indicates that open- and closed-dwell times are long-term correlated and do not change with the voltage applied to the patch at a 5% significance level (F = 2.2402; p = 0.140715). Randomly shuffling the experimental data removes the correlation in all voltages. When the Hurst method was applied to the results from a simulated three-state Markovian model, it could not account for the long-term correlation found in the experimental data. In this case, H has the following values: 0.5498 +/- 0.018 (n = 100) for V = +20 mV; 0.5557 +/- 0.0202 (n = 100) for V = +40 mV; 0.5565 +/- 0.0246 (n = 100) for V = 60 mV and 0.5595 +/- 0.0247 (n = 100) for V = +50 mV. Even a four-state Markovian model was not adequate to correctly simulate the long-term memory found experimentally, with H values significantly different from those found for the experimental data, in the same voltage range (F = 15.0355; p = 0.00001). In conclusion, this paper shows that: (1) the open- and closed-dwell times of the single calcium-activated potassium channel of Leydig cells are long-term correlated; (2) three- and four-state Markovian models, which describe very well the dwell time distributions, are not adequate to describe the long-term correlation found between the open and closed states of this ion channel. (C) 2000 Academic Press. [References: 32]
机译：通过假设打开和关闭状态之间的过渡是无记忆的过程来对离子通道的门控进行建模。然而，对单一电流事件记录的分析表明，动力学过程具有短期记忆，即打开和关闭停留时间是短期相关的。在这里，重标范围分析（RIS Hurst分析）用作测试Leydig细胞中存在的单个钙激活钾通道中长期相关性的方法。针对四个不同电压（V）计算出的赫斯特系数为：V = +20 mV时为0.634 +/- 0.022（n = 3）; V = +40 mV时为0.635 +/- 0.012（n = 4）; V = +60 mV时为0.606 +/- 0.020（n = 4），V = +80 mV时为0.608 +/- 0.026（n = 4）。这表明打开和关闭停留时间是长期相关的，并且不会随在5％显着性水平下施加到贴片的电压而变化（F = 2.2402; p = 0.140715）。随机改组实验数据可消除所有电压的相关性。当赫斯特方法应用于模拟三态马尔可夫模型的结果时，它不能说明实验数据中的长期相关性。在这种情况下，H具有以下值：V = +20 mV时为0.5498 +/- 0.018（n = 100）; V = +40 mV时为0.5557 +/- 0.0202（n = 100）; V = 60 mV时为0.5565 +/- 0.0246（n = 100），V = +50 mV时为0.5595 +/- 0.0247（n = 100）。即使是四态马尔可夫模型也不足以正确地模拟实验发现的长期记忆，在相同电压范围内，H值与实验数据的H值显着不同（F = 15.0355; p = 0.00001）。总之，本文表明：（1）Leydig细胞单个钙激活钾通道的开放和闭合停留时间是长期相关的; （2）很好地描述了停留时间分布的三态和四态马尔可夫模型，不足以描述该离子通道打开状态和关闭状态之间的长期相关性。 （C）2000学术出版社。 [参考：32]

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