Chon K H, Chen Y M, Holstein-Rathlou N H, Marsh D J, Marmarelis V Z
Department of Biomedical Engineering, University of Southern California, Los Angeles 90089.
IEEE Trans Biomed Eng. 1993 Jan;40(1):8-20. doi: 10.1109/10.204766.
In order to assess the linearity of the mechanisms subserving renal blood flow autoregulation, broad-band arterial pressure fluctuations at three different power levels were induced experimentally and the resulting renal blood flow responses were recorded. Linear system analysis methods were applied in both the time and frequency domain. In the frequency domain, spectral estimates employing FFT, autoregressive moving average (ARMA) and moving average (MA) methods were used; only the MA model showed two vascular control mechanisms active at 0.02-0.05 Hz and 0.1-0.18 Hz consistent with previous experimental findings [Holstein-Rathlou et al., Amer. J. Physiol., vol. 258, 1990.]. In the time domain, impulse response functions obtained from the MA model indicated likewise the presence of these two vascular control mechanisms, but the ARMA model failed to show any vascular control mechanism at 0.02-0.05 Hz. The residuals (i.e., model prediction errors) of the MA model were smaller than the ARMA model for all levels of arterial pressure forcings. The observed low coherence values and the significant model residuals in the 0.02-0.05 Hz frequency range suggest that the tubuloglomerular feedback (TGF) active in this frequency range is a nonlinear vascular control mechanism. In addition, experimental results suggest that the operation of the TGF mechanism is more evident at low/moderate pressure fluctuations and becomes overwhelmed when the arterial pressure forcing is too high.
为了评估维持肾血流自动调节机制的线性，通过实验诱导了三种不同功率水平的宽带动脉压波动，并记录了由此产生的肾血流反应。在时域和频域中均应用了线性系统分析方法。在频域中，使用了采用快速傅里叶变换（FFT）、自回归移动平均（ARMA）和移动平均（MA）方法的谱估计；只有MA模型显示出在0.02 - 0.05Hz和0.1 - 0.18Hz有两种血管控制机制活跃，这与先前的实验结果一致[霍尔斯坦 - 拉特洛等人，《美国生理学杂志》，第258卷，1990年]。在时域中，从MA模型获得的脉冲响应函数同样表明存在这两种血管控制机制，但ARMA模型未能显示在0.02 - 0.05Hz有任何血管控制机制。对于所有动脉压强迫水平，MA模型的残差（即模型预测误差）均小于ARMA模型。在0.02 - 0.05Hz频率范围内观察到的低相干值和显著的模型残差表明，在此频率范围内活跃的肾小管 - 肾小球反馈（TGF）是一种非线性血管控制机制。此外，实验结果表明，TGF机制在低/中度压力波动时的运作更为明显，而当动脉压强迫过高时则会不堪重负。
