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Augmented vasopressin secretion during low sodium diet: Sensitization by volume signals?
Author(s) -
Bie Peter,
Molstrom Simon
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1161.5
Subject(s) - vasopressin , medicine , endocrinology , osmole , plasma osmolality , chemistry , saline , sodium , blood pressure , organic chemistry
Regulation of vasopressin secretion was studied in conscious dogs and in healthy volunteers. Dogs were fed regular diet or low‐salt diet (0.03 mmol kg −1 d −1 ) for 7 d. NaCl was infused i.v. at 0.02 mmol kg −1 min −1 in negligible volume for 3 h. Vasopressin V2 receptors were blocked by OPC 31260. Body fluid volume was maintained by servo‐controlled fluid infusion. On regular diet NaCl infusion elevated plasma Na + and osmolality (pOsm) by 4.5% and elicited a 3‐fold increase in plasma vasopressin (pAVP, 1.58 ±0.24 to 4.39 ±0.40 pg ml −1 ). At low‐salt diet pAVP increased (1.74 ±0.13 to 4.94 ±0.68 pg ml −1 ) as a function of pOsm with similar slope (0.31 pg ml −1 (mOsm/kg) −1 ) but offset to the left by 6.2 mOsm/kg. Similar results were seen during β 1 ‐receptor blockade (metoprolol, 2 mg/kg plus 0.9 mg h −1 kg −1 ). Human volunteers were studied after 4 d of low‐salt diet. Saline (135 mM) was infused i.v. providing 0.012 mmol Na + min −1 kg −1 for 4 h (some 1500 ml). Arterial blood pressure (BP) did not change; heart rate (HR) fell by 5.8 ± 1.5 bpm (p<0.01); central venous pressure (CVP) increased by 1.7 ± 0.5 mmHg (p<0.025) concomitant with a fall in pAVP (3.0±0.4 to 1.8±0.1 pg ml −1 , p<0.01). Identical results were obtained after metoprolol (0.3 mg/kg plus 0.06 mg h −1 kg −1 ) except that HR remained constant. The data are compatible with CVP mediated control of pAVP during low‐salt diet. Supported by the Danish MRC and the Novo Nordisk Foundation.