Rankin A J, Ashton N, Swift F V
Division of Basic Medical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Canada.
Pflugers Arch. 1992 Sep;421(6):585-90. doi: 10.1007/BF00375055.
This study was designed to characterise the response of the hindlimb vasculature to reduced renal perfusion in the anaesthetized rabbit and to elucidate whether the stimulus was dependent upon reduced renal perfusion pressure (RPP) or blood flow (RBF). Acute decreases in renal perfusion resulted in rapid and reversible increases in femoral perfusion (FPP). This vascular response was completely abolished following renal denervation indicating that the afferent components of the reflex is neurally mediated. Acute hindlimb responses to changes in renal perfusion pressure were present whether the limb was perfused with homologous blood or cross-perfused with blood from a donor rabbit, demonstrating that the efferent component of the response is also neurally mediated. There was a 28-s latency for initiation of the hindlimb vasoconstriction, which is consistent with recent evidence for renal autocoid stimulation of the afferent renal nerve receptors. Decreasing RPP indirectly, by altering flow, resulted in a hindlimb vasoconstriction below approximately 55 mm Hg (7.3 kPa) RPP or 15 ml/min RBF. However, decreasing RPP by directly reducing pressure in graded steps resulted in increases in FPP, which reflected the changes in renal flow; thus during the autoregulatory phase, where flow did not change as pressure fell, FPP also remained stable. The results of these protocols suggest that a neurally mediated hindlimb vascular reflex is stimulated by decreased renal flow rather than pressure.
本研究旨在描述麻醉兔后肢血管系统对肾灌注减少的反应，并阐明该刺激是否依赖于肾灌注压（RPP）或血流量（RBF）的降低。肾灌注的急性减少导致股动脉灌注（FPP）迅速且可逆地增加。肾去神经支配后，这种血管反应完全消失，表明该反射的传入成分是由神经介导的。无论后肢是用同源血液灌注还是与供体兔的血液交叉灌注，对肾灌注压变化的急性后肢反应均存在，这表明该反应的传出成分也是由神经介导的。后肢血管收缩开始有28秒的潜伏期，这与最近关于肾自身活性物质刺激肾传入神经受体的证据一致。通过改变血流量间接降低RPP，会导致后肢血管收缩，当RPP低于约55 mmHg（7.3 kPa）或RBF低于15 ml/min时出现这种情况。然而，通过分级直接降低压力来降低RPP，会导致FPP增加，这反映了肾血流量的变化；因此，在自动调节阶段，当压力下降时血流量不变，FPP也保持稳定。这些实验方案的结果表明，肾血流量减少而非压力降低刺激了神经介导的后肢血管反射。
