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Oppelaar JJ, Bouwmeester TA, Silova AA, Collard D, Wouda RD, van Duin RE, Rorije NMG, Olde Engberink RHG, Danser AHJ, van den Born BJH, Vogt L. Salt-sensitive trait of normotensive individuals is associated with altered autonomous cardiac regulation: a randomized controlled intervention study. Am J Physiol Renal Physiol 2023; 325:F707-F716. [PMID: 37795535 DOI: 10.1152/ajprenal.00076.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 09/07/2023] [Accepted: 09/27/2023] [Indexed: 10/06/2023] Open
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.NEW & NOTEWORTHY Extracellular fluid expansion in normotensive individuals after salt loading is present in both salt-sensitive and salt-resistant individuals and is not discriminatory to the blood pressure response to sodium loading in a steady-state measurement. In normotensive subjects, the ability to sufficiently vasodilate seems to play a pivotal role in salt sensitivity. In a normotensive cohort, differences in sympathovagal balance are also present in low-salt conditions rather than being affected by salt loading. Whereas treatment and prevention of salt-sensitive blood pressure increase are mostly focused on renal sodium handling and extracellular volume regulation, our study suggests that an inability to adequately vasodilate and altered autonomous cardiac functioning are additional key players in the pathophysiology of salt-sensitive blood pressure increase.
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Affiliation(s)
- Jetta J Oppelaar
- Section of Nephrology, Department of Internal Medicine, Amsterdam UMC location, University of Amsterdam, Amsterdam, The Netherlands
- Microcirculation, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - Thomas A Bouwmeester
- Section of Vascular Medicine, Department of Internal Medicine, Amsterdam UMC location, University of Amsterdam, Amsterdam, The Netherlands
- Atherosclerosis and Ischemic Syndromes, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - Anastasia A Silova
- Section of Nephrology, Department of Internal Medicine, Amsterdam UMC location, University of Amsterdam, Amsterdam, The Netherlands
| | - Didier Collard
- Section of Vascular Medicine, Department of Internal Medicine, Amsterdam UMC location, University of Amsterdam, Amsterdam, The Netherlands
- Atherosclerosis and Ischemic Syndromes, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - Rosa D Wouda
- Section of Nephrology, Department of Internal Medicine, Amsterdam UMC location, University of Amsterdam, Amsterdam, The Netherlands
- Microcirculation, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - Robert E van Duin
- Section of Nephrology, Department of Internal Medicine, Amsterdam UMC location, University of Amsterdam, Amsterdam, The Netherlands
- Microcirculation, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - Nienke M G Rorije
- Section of Nephrology, Department of Internal Medicine, Amsterdam UMC location, University of Amsterdam, Amsterdam, The Netherlands
- Microcirculation, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - Rik H G Olde Engberink
- Section of Nephrology, Department of Internal Medicine, Amsterdam UMC location, University of Amsterdam, Amsterdam, The Netherlands
- Microcirculation, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - A H Jan Danser
- Division of Vascular Medicine and Pharmacology, Department of Internal Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Bert-Jan H van den Born
- Section of Vascular Medicine, Department of Internal Medicine, Amsterdam UMC location, University of Amsterdam, Amsterdam, The Netherlands
- Atherosclerosis and Ischemic Syndromes, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - Liffert Vogt
- Section of Nephrology, Department of Internal Medicine, Amsterdam UMC location, University of Amsterdam, Amsterdam, The Netherlands
- Microcirculation, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
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Oppelaar JJ, Vuurboom MD, Wenstedt EFE, van Ittersum FJ, Vogt L, Olde Engberink RHG. Reconsidering the Edelman equation: impact of plasma sodium concentration, edema and body weight. Eur J Intern Med 2022; 100:94-101. [PMID: 35393237 DOI: 10.1016/j.ejim.2022.03.027] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 03/22/2022] [Accepted: 03/24/2022] [Indexed: 11/18/2022]
Abstract
BACKGROUND Guidelines recommend treatment of dysnatremias to be guided by formulas based on the Edelman equation. This equation describes the relation between plasma sodium concentration and exchangeable cations. However, this formula does not take into account clinical parameters that have recently been associated with local tissue sodium accumulation, which occurs without concurrent water retention. We investigated to what extent such clinical factors affect the Edelman equation and dysnatremia treatment. METHODS We performed a post-hoc analysis with original data of the Edelman study. Linear regression was used to examine the effect of age, sex, weight, edema, total body water (TBW) and heart and kidney failure on the Edelman equation. With attenuated correction, we corrected for measurement errors of both variables. Using piecewise regression, we analyzed whether the Edelman association differs for different plasma sodium concentrations. RESULTS Data was available for 82 patients; 57 males and 25 females with a mean (SD) age of 57 (15) years. The slope of the Edelman equation was significantly affected by weight (p=0.01) and edema (p=0.03). Also, below and above plasma sodium levels of 133 mmol/L the slope of the Edelman equation was significantly different (1.25 x0025vs 0.58x0025, p<0.01). CONCLUSION Edelman's equation's coefficients are significantly affected by weight, edema and plasma sodium, possibly reflecting differences in tissue sodium accumulation capacity. The performance of Edelman-based formulas in clinical settings may be improved by taking these clinical characteristics into account.
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Affiliation(s)
- Jetta J Oppelaar
- Amsterdam UMC location University of Amsterdam, Department of Internal Medicine, Section of Nephrology, Meibergdreef 9, Amsterdam, The Netherlands; Amsterdam Cardiovascular Sciences, Microcirculation, Amsterdam, The Netherlands
| | - Mart D Vuurboom
- Amsterdam UMC location University of Amsterdam, Department of Internal Medicine, Section of Nephrology, Meibergdreef 9, Amsterdam, The Netherlands; Amsterdam Cardiovascular Sciences, Microcirculation, Amsterdam, The Netherlands
| | - Eliane F E Wenstedt
- Amsterdam UMC location University of Amsterdam, Department of Internal Medicine, Section of Nephrology, Meibergdreef 9, Amsterdam, The Netherlands; Amsterdam Cardiovascular Sciences, Microcirculation, Amsterdam, The Netherlands
| | - Frans J van Ittersum
- Amsterdam UMC location University of Amsterdam, Department of Internal Medicine, Section of Nephrology, Meibergdreef 9, Amsterdam, The Netherlands; Amsterdam UMC location Vrije Universiteit Amsterdam, Department of Internal Medicine, Section of Nephrology, Boelelaan 1117, Amsterdam, The Netherlands; Amsterdam Cardiovascular Sciences, Atherosclerosis & Ischemic Syndromes, Amsterdam, The Netherlands
| | - L Vogt
- Amsterdam UMC location University of Amsterdam, Department of Internal Medicine, Section of Nephrology, Meibergdreef 9, Amsterdam, The Netherlands; Amsterdam Cardiovascular Sciences, Microcirculation, Amsterdam, The Netherlands
| | - Rik H G Olde Engberink
- Amsterdam UMC location University of Amsterdam, Department of Internal Medicine, Section of Nephrology, Meibergdreef 9, Amsterdam, The Netherlands; Amsterdam Cardiovascular Sciences, Microcirculation, Amsterdam, The Netherlands.
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