title: Elevated renal perfusion pressure does not contribute to natriuresis induced by isotonic saline infusion in freely moving dogs.
abstract: The study was designed to determine to what extent moderate elevation of renal perfusion pressure (RPP) via the mechanism of 'pressure natriuresis' contributes to the natriuresis induced by acute i.v. saline loading. Nine Beagle dogs maintained on ample sodium intake (5.5 mmol (kg body mass)(-1) day(-1)) were chronically equipped with an aortic occluder to servocontrol RPP, a bladder catheter to measure renal function, and catheters for measurement of RPP and mean arterial blood pressure (MABP). A swivel system allowed free movement in the kennel during experiments. Isotonic saline loading (500 ml in 100 min) was studied as follows: with and without servocontrol of RPP, and these two protocols repeated in the presence of angiotensin-converting enzyme inhibition (ACEI, Enalapril, 2 mg (kg body mass)(-1)). Saline loading increased MABP by about 12 mmHg and sodium excretion from about 28 micromol min(-1) up to about 350 micromol min(-1). Without ACEI, servocontrol of RPP at 10% below control 24 h MABP slightly delayed the onset of the saline-induced natriuresis, but did not reduce peak sodium excretion or cumulative sodium excretion. The slight delay most probably resulted from pressure-controlled renin release because, with ACEI, servocontrol of RPP did not delay or reduce the saline-induced natriuresis. In conclusion, pressure natriuresis does not contribute to the natriuresis following acute saline loading.
authors.affiliation: Institute of Physiology, University Clinics Charité, Berlin, Germany. erdmann.seeliger@charite.de
authors.forename: Erdmann
authors.initials: E
authors.lastname: Seeliger
authors.forename: Jens Lundbaek
authors.initials: JL
authors.lastname: Andersen
authors.forename: Peter
authors.initials: P
authors.lastname: Bie
authors.forename: H Wolfgang
authors.initials: HW
authors.lastname: Reinhardt
mesh_terms: D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D004285:Dogs; D005260:Female; D005919:Glomerular Filtration Rate / Q000187:drug effects / Q000502:physiology; D007262:Infusions, Intravenous; D007552:Isotonic Solutions / Q000008:administration & dosage; D007668:Kidney / Q000187:drug effects / Q000502:physiology*; D009318:Natriuresis / Q000187:drug effects / Q000502:physiology*; D012965:Sodium Chloride / Q000008:administration & dosage*; D014554:Urination / Q000187:drug effects / Q000502:physiology
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D007552:Isotonic Solutions; D012965:Sodium Chloride