title: Antihypertensive effect of 0.1-Hz blood pressure oscillations to the kidney.
abstract: BACKGROUND
  Physiological blood pressure (BP) fluctuations with frequencies >0.1 Hz can override renal blood flow autoregulation. The influence of such immediate changes in renal perfusion pressure (RPP) on daily BP regulation, eg, via shear stress-stimulated liberation of renal endothelial NO, however, is unknown. Thus, we studied the effects of such RPP oscillations on renal function and on systemic BP during the onset of renal hypertension.
  
  
  RESULTS
  Seven beagles (randomly assigned to each of the following protocols) were chronically instrumented for the measurement of systemic BP, RPP, and renal excretory function. An inflatable cuff was used to reduce and to oscillate RPP over 24 hours in the freely moving dog. Reducing RPP to 87+/-2 mm Hg diminished excretion of sodium and water and doubled plasma renin activity (PRA, n=7, P<0. 01) but had no significant effect on urinary nitrate excretion (n=6), a marker of NO generation. Superimposing 0.1-Hz oscillations (+/-10 mm Hg) onto the reduced RPP blunted hypertension, returned fluid excretion almost to control levels, and doubled renal sodium elimination. Nitrate excretion peaked at 8 hours, only to return to control values shortly thereafter. PRA, conversely, was significantly reduced during the last third of the experimental protocols.
  
  
  CONCLUSIONS
  BP fluctuations transiently stimulate NO liberation and induce a reduction in PRA, which enhances 24-hour sodium and water excretion and markedly attenuates the acute development of renovascular hypertension.
authors.affiliation: Institut für Physiologie der Humboldt Universität Berlin, Berlin, Germany. b.nafz@gmx.de
authors.forename: B
authors.initials: B
authors.lastname: Nafz
authors.forename: J
authors.initials: J
authors.lastname: Stegemann
authors.forename: M H
authors.initials: MH
authors.lastname: Bestle
authors.forename: N
authors.initials: N
authors.lastname: Richter
authors.forename: E
authors.initials: E
authors.lastname: Seeliger
authors.forename: I
authors.initials: I
authors.lastname: Schimke
authors.forename: H W
authors.initials: HW
authors.lastname: Reinhardt
authors.forename: P B
authors.initials: PB
authors.lastname: Persson
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D004285:Dogs; D005260:Female; D005583:Fourier Analysis; D006977:Hypertension, Renal / Q000503:physiopathology*; D007668:Kidney / Q000098:blood supply / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism; D012079:Renal Circulation; D012083:Renin / Q000097:blood
chemical_list: D009569:Nitric Oxide; D012083:Renin