Adverse cardiovascular effects of acute salt loading in young normotensive individuals

We sought to explore the effects of salt loading in young normotensives on vascular endothelial function, echocardiographic left ventricular diastolic function, and electrocardiographic QT dispersion. Sixteen healthy normotensive male volunteers were randomized in a double-blind crossover fashion to...

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Bibliographic Details
Published in:Hypertension (Dallas, Tex. 1979) Vol. 51; no. 6; p. 1525
Main Authors: Tzemos, Nikolaos, Lim, Pitt O, Wong, Suzanne, Struthers, Allan D, MacDonald, Thomas M
Format: Journal Article
Language:English
Published: United States 01.06.2008
Subjects:
Acetylcholine - administration & dosage
Acute Disease
Adult
Blood Pressure - drug effects
Blood Pressure - physiology
Cross-Over Studies
Diastole - drug effects
Diastole - physiology
Diet, Sodium-Restricted
Echocardiography
Endothelium, Vascular - drug effects
Endothelium, Vascular - physiology
Enzyme Inhibitors - administration & dosage
Humans
Hypertension - physiopathology
Male
Nitroprusside - administration & dosage
omega-N-Methylarginine - administration & dosage
Sodium Chloride, Dietary - adverse effects
Vasoconstriction - drug effects
Vasoconstriction - physiology
Vasodilator Agents - administration & dosage
Ventricular Function, Left - drug effects
Ventricular Function, Left - physiology
ISSN:1524-4563, 1524-4563
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Summary:We sought to explore the effects of salt loading in young normotensives on vascular endothelial function, echocardiographic left ventricular diastolic function, and electrocardiographic QT dispersion. Sixteen healthy normotensive male volunteers were randomized in a double-blind crossover fashion to 5-day treatment periods with either placebo or salt tablets (200 mmol/d of sodium) separated by a 2-week washout period. Throughout the study the volunteers were asked to maintain a low-salt diet. Forearm venous occlusion plethysmography and intraarterial infusions of acetylcholine (ACh), sodium nitroprusside (SNP), and N(G)-monomethyl-l-arginine (L-NMMA) were used to assess vascular reactivity. Baseline and postsalt loading 12-lead ECGs and echocardiograms were also obtained. Twenty-four-hour ambulatory systolic blood pressure rose (117+/-11 to 121+/-8 mm Hg) significantly with salt loading. The endothelium-dependent responses to ACh were significantly blunted with salt compared to placebo (DeltaFBF% 403 [50] versus 296 [31]; P<0.05) and L-NMMA (DeltaFBF% -47.2 [4] versus -31 [3]; P<0.01). In contrast, the endothelium-independent response to SNP was not different between treatments. Color M-mode flow propagation velocity (CMMFPV), a preload index of left ventricular diastolic function, was significantly reduced with salt (64 [6] versus 59 [16] cm/s; P<0.05) suggesting increased ventricular stiffness. QT dispersion was also significantly increased with salt (58 [16] versus 48 [17] ms; P=0.02). Salt loading impaired vascular endothelial function, left ventricular mechanical relaxation, and electric repolarization in young healthy normotensives.
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ISSN:1524-4563
1524-4563
DOI:10.1161/HYPERTENSIONAHA.108.109868