title: NT-ProBNP levels, water and sodium homeostasis in healthy men: effects of 7 days of dry immersion.
abstract: Immersion is a useful tool for studying fluid-volume homeostasis. Natriuretic peptides play a vital role in renal, humoral, and cardiovascular regulation under changing environmental conditions. We hypothesized that dry immersion would rapidly induce a new steady state for water and sodium metabolism, and that serum NT-proBNP levels, a proxy measure for brain natriuretic peptide (BNP), would decrease during long-term dry immersion and increase during recovery. Eight healthy young men were studied before, during, and after 7 days of dry immersion. Body weight, water balance, and plasma volume changes were evaluated. Plasma and serum samples were analyzed for active renin, NT-proBNP, aldosterone, electrolytes, osmolality, total protein, and creatinine. Urine samples were analyzed to determine levels of electrolytes, osmolality, creatinine, and free cortisol. A stand test was performed before and after dry immersion to evaluate cardiovascular deconditioning. Long-term dry immersion induced acute changes in water and sodium homeostasis on day 1, followed by a new steady state. Plasma volume decreased significantly during dry immersion. The serum levels of NT-proBNP increased significantly in recovery (10 ± 3 ng/L before dry immersion vs. 26 ± 5 ng/L on the fourth recovery day). Heart rate in the standing position was significantly greater after immersion. Results suggest that chronic dry immersion rapidly induced a new level of water-electrolyte homeostasis. The increase in NT-proBNP levels during the recovery period may be related to greater cardiac work and might reflect the degree of cardiovascular deconditioning.
authors.affiliation: Faculté de Médecine, CNRS UMR 6214, INSERM U771, 49045 Angers Cedex, France. nastassia.navasiolava@etud.univ-angers.fr
authors.forename: Nastassia M
authors.initials: NM
authors.lastname: Navasiolava
authors.forename: Aurelie
authors.initials: A
authors.lastname: Pajot
authors.forename: Yves
authors.initials: Y
authors.lastname: Gallois
authors.forename: Ludmila Kh
authors.initials: LKh
authors.lastname: Pastushkova
authors.forename: Vladimir A
authors.initials: VA
authors.lastname: Kulchitsky
authors.forename: Guillemette
authors.initials: G
authors.lastname: Gauquelin-Koch
authors.forename: Inesa B
authors.initials: IB
authors.lastname: Kozlovskaya
authors.forename: Martina
authors.initials: M
authors.lastname: Heer
authors.forename: Olga
authors.initials: O
authors.lastname: Hand
authors.forename: Irina M
authors.initials: IM
authors.lastname: Larina
authors.forename: Marc-Antoine
authors.initials: MA
authors.lastname: Custaud
mesh_terms: D000328:Adult; D001834:Body Water / Q000378:metabolism / Q000502:physiology*; D003890:Desiccation; D006262:Health; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D007101:Immersion / Q000009:adverse effects / Q000503:physiopathology*; D008297:Male; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D010446:Peptide Fragments / Q000097:blood*; D020127:Recovery of Function; D012964:Sodium / Q000378:metabolism*; D013997:Time Factors; D014882:Water-Electrolyte Balance / Q000502:physiology; D055815:Young Adult
chemical_list: D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain; D012964:Sodium