Salt-sensitive trait of normotensive individuals is associated with altered autonomous cardiac regulation: a randomized controlled intervention study

Jetta J. Oppelaar, Thomas A. Bouwmeester, Anastasia A. Silova, Didier Collard, Rosa D. Wouda, Robert E. van Duin, Nienke M.G. Rorije, Rik H.G. Olde Engberink, A. H.Jan Danser, Bert Jan H. van den Born, Liffert Vogt*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Blood pressure (BP) responses to sodium intake show great variation, discriminating salt-sensitive (SS) from salt-resistant (SR) individuals. The pathophysiology behind salt sensitivity is still not fully elucidated. We aimed to investigate salt-induced effects on body fluid, vascular tone, and autonomic cardiac response with regard to BP change in healthy normotensive individuals. We performed a randomized crossover study in 51 normotensive individuals with normal body mass index and estimated glomerular filtration rate. Subjects followed both a low-Na + diet (LSD, <50 mmol/day) and a high-Na + diet (HSD, >200 mmol/day). Cardiac output, systemic vascular resistance (SVR), and cardiac autonomous activity, through heart rate variability and cross-correlation baroreflex sensitivity (xBRS), were assessed with noninvasive continuous finger BP measurements. In a subset, extracellular volume (ECV) was assessed by iohexol measurements. Subjects were characterized as SS if mean arterial pressure (MAP) increased ≥3 mmHg after HSD. After HSD, SS subjects (25%) showed a 6.1-mmHg (SD 1.9) increase in MAP. No differences between SS and SR in body weight, cardiac output, or ECV were found. SVR was positively correlated with Delta BP (r = 0.31, P = 0.03). xBRS and heart rate variability were significantly higher in SS participants compared to SR participants after both HSD and LSD. Sodium loading did not alter heart rate variability within groups. Salt sensitivity in normotensive individuals is associated with an inability to decrease SVR upon high salt intake that is accompanied by alterations in autonomous cardiac regulation, as reflected by decreased xBRS and heart rate variability. No discriminatory changes upon high salt were observed among salt-sensitive individuals in body weight and ECV.

Original languageEnglish
Pages (from-to)F707-F716
JournalAmerican journal of physiology. Renal physiology
Volume325
Issue number6
DOIs
Publication statusPublished - Dec 2023

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