Rudenstam J, Bergström G, Göthberg G, Karlström G
Department of Physiology, Göteborg University, Sweden.
Acta Physiol Scand. 1995 Oct;155(2):183-91. doi: 10.1111/j.1748-1716.1995.tb09963.x.
The aim of this study was to investigate the effects of renal nerve stimulation on the humoral renal antihypertensive system. An isolated kidney (IK) was perfused at normal or high arterial pressures from a normotensive assay rat by means of a perfusion pump. Perfusion pressure (PP) to the IK was 90 mmHg for a control period of 30 min. In three of five experimental groups PP was then increased to 175 mmHg. In two of the groups the renal nerves were stimulated at 2 (P-175(2Hz)) or 5 Hz (P-175(5Hz)) for 60 min. The remaining group served as a control (P-175C). In two groups IK pressure was maintained at 90 mmHg with 5 Hz nerve stimulation (P-90(5Hz) or without nerve stimulation (P-90C). MAP of the assay rat decreased by 22 and 27% (P < 0.001) in the P-175C and P-175(2Hz) groups, respectively during the 60 min period of nerve stimulation, but remained stable in P-175(5Hz). Renal blood flow increased in the IK when PP was increased in P-175C, but did not change significantly in P-175(2Hz) or P-175(5Hz). Blood pressure remained constant in the assay rat when the IK was perfused at 90 mmHg. The renal excretory functions of the IK decreased in a frequency dependent manner by 2 and 5 Hz renal nerve stimulation compared with P-175C. We conclude that 5 Hz renal nerve stimulation inhibits the pressure dependent release of humoral depressor substances from an IK perfused at 175 mmHg, whereas this is not seen when stimulating at 2 Hz. It is suggested that hte release of antihypertensive substances from the renal medulla requires an increased renomedullary blood flow.
本研究的目的是探讨肾神经刺激对体液性肾降压系统的影响。通过灌注泵从血压正常的试验大鼠以正常或高动脉压灌注离体肾脏（IK）。在30分钟的对照期内，IK的灌注压（PP）为90 mmHg。在五个实验组中的三个组中，随后将PP提高到175 mmHg。在其中两个组中，以2 Hz（P - 175(2Hz)）或5 Hz（P - 175(5Hz)）刺激肾神经60分钟。其余组作为对照（P - 175C）。在两组中，IK压力通过5 Hz神经刺激（P - 90(5Hz)）或无神经刺激（P - 90C）维持在90 mmHg。在神经刺激的60分钟期间，试验大鼠的平均动脉压（MAP）在P - 175C和P - 175(2Hz)组中分别下降了22%和27%（P < 0.001），但在P - 175(5Hz)组中保持稳定。当P - 175C中PP升高时，IK中的肾血流量增加，但在P - 175(2Hz)或P - 175(5Hz)中没有显著变化。当IK以90 mmHg灌注时，试验大鼠的血压保持恒定。与P - 175C相比，IK的肾排泄功能通过2 Hz和5 Hz肾神经刺激以频率依赖性方式降低。我们得出结论，5 Hz肾神经刺激抑制了在175 mmHg灌注的IK中体液性降压物质的压力依赖性释放，而在2 Hz刺激时未观察到这种情况。提示从肾髓质释放降压物质需要肾髓质血流量增加。
