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Increased salt consumption induces body water conservation and decreases fluid intake

Rakova, N. and Kitada, K. and Lerchl, K. and Dahlmann, A. and Birukov, A. and Daub, S. and Kopp, C. and Pedchenko, T. and Zhang, Y. and Beck, Luis and Johannes, Bernd W. and Marton, A. and Müller, D.N. and Rauh, M. and Luft, F.C. and Titze, J. (2017) Increased salt consumption induces body water conservation and decreases fluid intake. The Journal of Clinical Investigation, 127 (5), pp. 1932-1943. American Society for Clinical Investigation. doi: 10.1172/JCI88530. ISSN 0021-9738.

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BACKGROUND. The idea that increasing salt intake increases drinking and urine volume is widely accepted. We tested the hypothesis that an increase in salt intake of 6 g/d would change fluid balance in men living under ultra-long-term controlled conditions. METHODS. Over the course of 2 separate space flight simulation studies of 105 and 205 days’ duration, we exposed 10 healthy men to 3 salt intake levels (12, 9, or 6 g/d). All other nutrients were maintained constant. We studied the effect of salt-driven changes in mineralocorticoid and glucocorticoid urinary excretion on day-to-day osmolyte and water balance. RESULTS. A 6-g/d increase in salt intake increased urine osmolyte excretion, but reduced free-water clearance, indicating endogenous free water accrual by urine concentration. The resulting endogenous water surplus reduced fluid intake at the 12-g/d salt intake level. Across all 3 levels of salt intake, half-weekly and weekly rhythmical mineralocorticoid release promoted free water reabsorption via the renal concentration mechanism. Mineralocorticoid-coupled increases in free water reabsorption were counterbalanced by rhythmical glucocorticoid release, with excretion of endogenous osmolyte and water surplus by relative urine dilution. A 6-g/d increase in salt intake decreased the level of rhythmical mineralocorticoid release and elevated rhythmical glucocorticoid release. The projected effect of salt-driven hormone rhythm modulation corresponded well with the measured decrease in water intake and an increase in urine volume with surplus osmolyte excretion. CONCLUSION. Humans regulate osmolyte and water balance by rhythmical mineralocorticoid and glucocorticoid release, endogenous accrual of surplus body water, and precise surplus excretion. FUNDING. Federal Ministry for Economics and Technology/DLR; the Interdisciplinary Centre for Clinical Research; the NIH; the American Heart Association (AHA); the Renal Research Institute; and the TOYOBO Biotechnology Foundation. Food products were donated by APETITO, Coppenrath und Wiese, ENERVIT, HIPP, Katadyn, Kellogg, Molda, and Unilever.

Item URL in elib:https://elib.dlr.de/114026/
Document Type:Article
Title:Increased salt consumption induces body water conservation and decreases fluid intake
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Rakova, N.experimental and clinical research center, an institutional cooperation between the charité medical faculty and the max delbrück center, berlin, germanyUNSPECIFIEDUNSPECIFIED
Kitada, K.Vanderbilt University Medical Center, NashvilleUNSPECIFIEDUNSPECIFIED
Lerchl, K.interdisciplinary center for clinical research, nikolaus fiebiger center for molecular medicineUNSPECIFIEDUNSPECIFIED
Dahlmann, A.University Clinic ErlangenUNSPECIFIEDUNSPECIFIED
Birukov, A.Interdisciplinary Center for ClinicalUNSPECIFIEDUNSPECIFIED
Daub, S.Vanderbilt University Medical Center, NashvilleUNSPECIFIEDUNSPECIFIED
Kopp, C.University Clinic ErlangenUNSPECIFIEDUNSPECIFIED
Pedchenko, T.Vanderbilt University Medical Center, NashvilleUNSPECIFIEDUNSPECIFIED
Zhang, Y.Vanderbilt University Medical Center, NashvilleUNSPECIFIEDUNSPECIFIED
Marton, A.Vanderbilt University Medical Center, NashvilleUNSPECIFIEDUNSPECIFIED
Müller, D.N.Experimental and Clinical Research Center, Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, BerlinUNSPECIFIEDUNSPECIFIED
Rauh, M.universität erlangenUNSPECIFIEDUNSPECIFIED
Luft, F.C.franz-volhard clinical research center, medical university charité, campus buch, berlin, germanyUNSPECIFIEDUNSPECIFIED
Titze, J.department of nephrology and hypertension, and nikolaus fiebiger centre for molecular medicine, university clinic and friedrich alexander university of erlangen-nuremberg, germanyUNSPECIFIEDUNSPECIFIED
Date:September 2017
Journal or Publication Title:The Journal of Clinical Investigation
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:Yes
Page Range:pp. 1932-1943
Publisher:American Society for Clinical Investigation
Keywords:Salt; fluid intake; Body water; water Balance; osmolyte;
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Research under Space Conditions
DLR - Research area:Raumfahrt
DLR - Program:R FR - Research under Space Conditions
DLR - Research theme (Project):R - Vorhaben Systemphysiologie (old)
Location: Köln-Porz
Institutes and Institutions:Institute of Aerospace Medicine > Muscle and Bone Metabolism
Deposited By: Becker, Christine
Deposited On:28 Nov 2017 11:29
Last Modified:23 Feb 2019 00:21

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