Rudenstam J, Bergström G, Taghipour K, Göthberg G, Karlström G
Department of Physiology, Göteborg University, Sweden.
Acta Physiol Scand. 1995 Jul;154(3):387-94. doi: 10.1111/j.1748-1716.1995.tb09922.x.
Intrarenal blood flow regulation probably affects long-term blood pressure homeostasis. We have previously shown that 5 Hz renal sympathetic stimulation inhibits a humoral renal depressor mechanism, otherwise activated when increasing perfusion pressure to an isolated kidney in a cross-circulation set-up. This inhibition was suggested to occur as a result of a reduction of renomedullary blood flow. Little is known about nervous blood flow regulation within the medulla. Therefore in this study, total renal (RBF), cortical (CBF) and papillary (PBF) blood flows were separately measured by ultrasonic and laser-Doppler techniques in Wistar rats during graded renal sympathetic stimulations. Periods of 15 min stimulation at 0.5, 2 and 5 Hz were performed in random order. RBF decreased at 0.5 Hz by 1%, at 2 Hz by 16% (P < 0.001) and at 5 Hz by 49% (P < 0.001). In a similar fashion (r = 0.73, P < 0.001), CBF decreased by 1%, 10% (P < 0.001) and 37% (P < 0.001), respectively. By contrast, PBF increased by 2% at 0.5 Hz and 4% at 2 Hz, while it decreased at 5 Hz, by 4% (P < 0.05, compared with 2 Hz). It seems therefore, that superficial renocortical and total renal blood flows are closely regulated by renal sympathetic nerves with increasing vasoconstriction at higher frequencies, while medullary blood flow, on the other hand, seems to be under strong local control, tending to offset neurogenic flow restrictions.
肾内血流调节可能影响长期血压稳态。我们之前已经表明，5Hz肾交感神经刺激会抑制一种体液性肾降压机制，而在交叉循环实验中，当增加灌注压至离体肾脏时，该机制会被激活。这种抑制作用被认为是肾髓质血流减少的结果。目前对髓质内神经血流调节知之甚少。因此，在本研究中，我们采用超声和激光多普勒技术，在Wistar大鼠分级肾交感神经刺激过程中分别测量了总肾血流（RBF）、皮质血流（CBF）和乳头血流（PBF）。以随机顺序进行0.5Hz、2Hz和5Hz的15分钟刺激。RBF在0.5Hz时下降1%，在2Hz时下降16%（P<0.001），在5Hz时下降49%（P<0.001）。以类似方式（r = 0.73，P<0.001），CBF分别下降1%、10%（P<0.001）和37%（P<0.001）。相比之下，PBF在0.5Hz时增加2%，在2Hz时增加4%，而在5Hz时下降4%（与2Hz相比，P<0.05）。因此，似乎肾皮质浅层和总肾血流受肾交感神经密切调节，频率越高血管收缩越强，而髓质血流似乎受强大的局部控制，倾向于抵消神经源性血流限制。
