FLUID WAVES IN RENAL TUBULES
FLUID WAVES IN RENAL TUBULES
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DOI：
10.1016/s0006-3495(86)83521-4
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发表时间：
1986-11-01
影响因子：
3.4
通讯作者：
MARSH, DJ
中科院分区：
文献类型：
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作者：
SAKAI, T;CRAIG, DA;MARSH, DJ
当动脉血压扰动发生在0.05赫兹以上的频率时，肾血流的自动调节是无效的。为了确定波到致密黄斑的传播速度是否为速率限制，我们估计了近端小管和Henle环的顺应性，并将这些值用于压力和流量作为时间和距离在肾单位的函数的模型中。在正常和林格氏负荷条件下，通过测量大鼠近端早期、近端晚期和远端早期肾小管的压力和流量来评估顺应性。顺应性再吸收管内稳定压力和流动的模型与这些结果相吻合。该暂态模型是一组具有分裂、非线性边界条件的非线性双曲型偏微分方程组，采用有限差分方法求解。Henle顺应性环大于近端小管顺应性，肾小球滤过率下降幅度大，时间延迟。模拟的阶梯强迫显示了类似的模式。肾小球滤过率的周期性变化在频率为0.05赫兹时减弱，与致密斑流量的变化之间有5 S的延迟。环路的高顺应性减慢了波传播到致密黄斑的速度，并降低了起源于肾小球的高频波的幅度，但信号链的其他部分也导致致密黄斑反馈反应缓慢。
Autoregulation of renal blood flow is ineffective when arterial pressure perturbations occur at frequencies above 0.05 Hz. To determine whether wave propagation velocity to the macula densa is rate limiting, we estimated compliances of the proximal tubule and the loop of Henle, and used these values in a model of pressure and flow as functions of time and distance in the nephron. Compliances were estimated from measurements of pressures and flows in early proximal, late promixal, and early distal tubules in rats under normal and Ringer-loaded conditions. A model of steady pressure and flow in a compliant, reabsorbing tubule was fitted to these results. The transient model was a set of nonlinear, hyperbolic partial differential equations with split, nonlinear boundary conditions, and was solved with finite difference methods. The loop of Henle compliance was larger than the proximal tubule compliance, and impluses in glomerular filtration rate were attenuated in magnitude and delayed in time in the loop of Henle. Simulated step forcings revealed a similar pattern. Periodic variations of GFR were attenuated at frequencies > 0.05 Hz, and there was a delay of 5 s between variations in GFR and macula densa flow rate. The high compliance of the loop slows wave propagation to the macula densa and reduces the amplitude of high frequency waves originating in the glomerulus, but other parts of the signal chain also contribute to the slow response of macula densa feedback.