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Fluid shifts and endocrine responses during chair rest and water immersion in manThe effects of external water pressure on intercompartmental fluid volume shifts and endocrine responses in man are investigated. Extracellular fluid volumes and plasma and urine electrolyte and endocrine responses of four male subjects were measured during eight hours of head-out water immersion and 16 hours of recovery bed rest and compared to responses obtained during eight hours of chair rest and 16 hours of bed rest without external hydrostatic pressure obtained in the same subjects five months later. Immersion is found to result in a substantial diuresis with respect to chair rest, accounted for by decreases in extracellular volume. A negative water balance during immersion and a positive water balance during chair rest were observed to be accompanied by a shift of extracellular volume to the intracellular compartment, as well as the suppression of plasma arginine vasopressin and renin activities in both regimes. The vasopressin and renin activity decreases are attributed to the increased central blood volume, and half of the plasma loss in immersed subjects is attributed to the effects of external water pressure.
Document ID
19800041820
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Greenleaf, J. E.
(NASA Ames Research Center Moffett Field, CA, United States)
Shvartz, E.
(NASA Ames Research Center Moffett Field, CA, United States)
Kravik, S.
(NASA Ames Research Center Moffett Field, CA, United States)
Keil, L. C.
(NASA Ames Research Center Laboratory of Human Environmental Physiology, Moffett Field, Calif., United States)
Date Acquired
August 10, 2013
Publication Date
January 1, 1980
Publication Information
Publication: Journal of Applied Physiology: Respiratory
Subject Category
Aerospace Medicine
Accession Number
80A25990
Distribution Limits
Public
Copyright
Other

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