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首页> 外文期刊>American Journal of Physiology >Analysis of nonstationarity in renal autoregulation mechanisms using time-varying transfer and coherence functions
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Analysis of nonstationarity in renal autoregulation mechanisms using time-varying transfer and coherence functions

机译：时变转移和相干函数分析肾脏自动调节机制中的非平稳性

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摘要

autoregulation of renal blood flow is mediated by the myogenic responses of the preglomerular vasculature (MYO) and the TGF feedback system. These two mechanisms exhibit characteristic resonant frequencies (MYO, 0.1-0.3 Hz; TGF, 0.02-0.05 Hz in rats). The marked difference in characteristic frequencies (and, hence, in time constants) between the TGF and MYO mechanisms permit separation and quantification of contributions of the two mechanisms by transfer function (1,4, 29) and coherence analyses (2, 12).A transfer function is the input-output relationship between an independent variable (blood pressure) and a dependent variable [renal blood flow (RBF)]. Its output is given in terms of gain, which reports fluctuation of the output with respect to the input and phase that contains the temporal relationshipbetween the two signals. Thus, normalized gain <0 dB indicates that RBF is stabilized with respect to blood pressure and hence that autoregulation is effective. The coherence function assesses the degree to which the data are related and provides information about the confidence one may have in the transfer function analysis. A high coherence at any frequency indicates that the input and output signals are closely and linearly related; reduced coherence can indicate the presence of noise, unrelated signals, or increased dynamic complexity.
机译：肾血流的自动调节是由肾小球前脉管系统（MYO）和TGF反馈系统的成肌反应介导的。这两种机制表现出特征性的共振频率（大鼠的MYO，0.1-0.3 Hz; TGF，0.02-0.05 Hz）。 TGF和MYO机制之间的特征频率（因此，时间常数）的显着差异允许通过传递函数（1,4，29）和相干分析（2，12）分离和量化这两种机制的贡献。传递函数是自变量（血压）和因变量[肾血流量（RBF）]之间的输入输出关系。其输出以增益给出，该增益报告输出相对于输入和相位的波动，该波动包含两个信号之间的时间关系。因此，归一化增益<0 dB表示RBF相对于血压稳定，因此自动调节有效。相干函数评估数据的关联程度，并提供有关传递函数分析中可能具有的置信度的信息。在任何频率下，较高的相干性表示输入和输出信号紧密且线性相关。降低的相干性可能表明存在噪声，无关信号或动态复杂性增加。

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