DiBona Gerald F, Sawin Linda L
Department of Internal Medicine and Department of Physiology and Biophysics, University of Iowa College of Medicine and Veterans Administration Medical Center, Iowa City, Iowa 52242, USA.
Am J Physiol Renal Physiol. 2002 Nov;283(5):F1056-65. doi: 10.1152/ajprenal.00052.2002.
When the renal nerves are stimulated with sinusoidal stimuli over the frequency range 0.04-0.8 Hz, low (< or =0.4 Hz)- but not high (> or =0.4 Hz)-frequency oscillations appear in renal blood flow (RBF) and are proposed to increase responsiveness of the renal vasculature to stimuli. This hypothesis was tested in anesthetized rats in which RBF responses to intrarenal injection of norepinephrine and angiotensin and to reductions in renal arterial pressure (RAP) were determined during conventional rectangular pulse and sinusoidal renal nerve stimulation. Conventional rectangular pulse renal nerve stimulation decreased RBF at 2 Hz but not at 0.2 or 1.0 Hz. Sinusoidal renal nerve stimulation elicited low-frequency oscillations (< or =0.4 Hz) in RBF only when the basal carrier signal frequency produced renal vasoconstriction, i.e., at 5 Hz but not at 1 Hz. Regardless of whether renal vasoconstriction occurred, neither conventional rectangular pulse nor sinusoidal renal nerve stimulation altered renal vasoconstrictor responses to norepinephrine and angiotensin. The RBF response to reduction in RAP was altered by both conventional rectangular pulse and sinusoidal renal nerve stimulation only when renal vasoconstriction occurred: the decrease in RBF during reduced RAP was greater. Sinusoidal renal nerve stimulation with a renal vasoconstrictor carrier frequency results in a decrease in RBF with superimposed low-frequency oscillations. However, these low-frequency RBF oscillations do not alter renal vascular responsiveness to vasoconstrictor stimuli.
当在0.04 - 0.8Hz频率范围内用正弦刺激刺激肾神经时，肾血流量（RBF）会出现低频率（≤0.4Hz）而非高频率（≥0.4Hz）的振荡，并且有人提出这些振荡会增加肾血管系统对刺激的反应性。在麻醉大鼠中对这一假设进行了测试，在传统矩形脉冲和正弦肾神经刺激期间，测定了肾血流量对肾内注射去甲肾上腺素和血管紧张素以及对肾动脉压（RAP）降低的反应。传统矩形脉冲肾神经刺激在2Hz时会降低肾血流量，但在0.2或1.0Hz时不会。仅当基础载波信号频率导致肾血管收缩时，即5Hz而非1Hz时，正弦肾神经刺激才会在肾血流量中引发低频率振荡（≤0.4Hz）。无论是否发生肾血管收缩，传统矩形脉冲和正弦肾神经刺激均未改变肾血管对去甲肾上腺素和血管紧张素的收缩反应。仅当发生肾血管收缩时，传统矩形脉冲和正弦肾神经刺激才会改变肾血流量对肾动脉压降低的反应：肾动脉压降低期间肾血流量的减少幅度更大。具有肾血管收缩载波频率的正弦肾神经刺激会导致肾血流量减少并伴有叠加的低频率振荡。然而，这些低频率肾血流量振荡不会改变肾血管对血管收缩刺激的反应性。
