title: Comparison of the effects of ouabain and brain natriuretic peptide in saline-loaded sheep.
abstract: 1. It has been claimed that ouabain is an endogenous hormone that may be pivotal in the pathogenesis of some forms of hypertension and may exaggerate natriuresis in situations characterized by volume overload. We compared the haemodynamic, renal and endocrine effects of ouabain (at approximately 187 ng/kg per min for 2 h) with those of brain natriuretic peptide (BNP; at 5 pmol/kg per min for 2 h) in nine saline-loaded sheep in a balanced, randomized, single-blind, placebo-controlled crossover study. 2. Brain natriuretic peptide infusion reduced mean arterial pressure whereas ouabain infusion caused no change. Haematocrit rose steadily during BNP infusion but fell during ouabain infusion. Neither ouabain nor BNP affected urine volume, sodium, potassium or creatinine excretion. Mean heart rate declined during the ouabain and placebo infusions, but was not altered during BNP infusion. Endogenous ouabain concentrations were not detectable at baseline or during BNP or placebo infusions, but rose to concentrations of 11 +/- 1.3 nmol/L during the ouabain infusion. 3. These results suggest that ouabain is not an endogenous hormone present at physiologically relevant concentrations. Furthermore, ouabain does not cause natriuresis during saline-loading in sheep and is therefore unlikely to be responsible for the exaggerated natriuresis seen in some forms of hypertension.
authors.affiliation: Department of Nephrology, Christchurch Hospital, New Zealand.
authors.forename: G B
authors.initials: GB
authors.lastname: Pidgeon
authors.forename: A M
authors.initials: AM
authors.lastname: Richards
authors.forename: M G
authors.initials: MG
authors.lastname: Nicholls
authors.forename: L K
authors.initials: LK
authors.lastname: Lewis
authors.forename: T G
authors.initials: TG
authors.lastname: Yandle
authors.forename: M T
authors.initials: MT
authors.lastname: Rademaker
authors.forename: C J
authors.initials: CJ
authors.lastname: Charles
authors.forename: R R
authors.initials: RR
authors.lastname: Bailey
authors.forename: K L
authors.initials: KL
authors.lastname: Lynn
mesh_terms: D000450:Aldosterone / Q000097:blood; D000818:Animals; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D007668:Kidney / Q000187:drug effects / Q000502:physiology; D020097:Natriuretic Peptide, Brain; D009419:Nerve Tissue Proteins / Q000494:pharmacology*; D010042:Ouabain / Q000494:pharmacology*; D010919:Placebos; D012083:Renin / Q000097:blood; D012756:Sheep; D012965:Sodium Chloride / Q000008:administration & dosage
chemical_list: D009419:Nerve Tissue Proteins; D010919:Placebos; D020097:Natriuretic Peptide, Brain; D012965:Sodium Chloride; D000450:Aldosterone; D010042:Ouabain; D012083:Renin