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Elevated renal perfusion pressure does not contribute to natriuresis induced by isotonic saline infusion in freely moving dogs
Author(s) -
Seeliger Erdmann,
Andersen Jens Lundbæk,
Bie Peter,
Reinhardt H. Wolfgang
Publication year - 2004
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2004.066670
Subject(s) - natriuresis , saline , medicine , blood pressure , perfusion , endocrinology , isotonic saline , excretion , diuresis , sodium , chemistry , renin–angiotensin system , renal function , organic chemistry
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 μmol min −1 up to about 350 μmol 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.