title: The effect of dDAVP with saline loading on fluid balance during LBNP and standing after 24-hr head-down bedrest.
abstract: Shuttle astronauts currently drink approximately a quart of water with eight salt tablets before reentry to restore lost body fluid and thereby reduce the likelihood of cardiovascular instability and syncope during reentry and after landing.  However, the saline loading countermeasure is not entirely effective in restoring orthostatic tolerance to preflight levels.  We tested the hypothesis that the effectiveness of this countermeasure could be improved with the use of a vasopressin analog, 1-deamino-8-D-arginine vasopressin (dDAVP).  The rationale for this approach is that reducing urine formation with exogenous vasopressin should increase the magnitude and duration of the vascular volume expansion produced by the saline load, and in so doing improve orthostatic tolerance during reentry and postflight.
authors.affiliation: NASA Johnson Space Center, Houston, TX, USA.
authors.forename: K E
authors.initials: KE
authors.lastname: Simanonok
authors.forename: S M
authors.initials: SM
authors.lastname: Fortney
authors.forename: S R
authors.initials: SR
authors.lastname: Ford
authors.forename: J B
authors.initials: JB
authors.lastname: Charles
authors.forename: D F
authors.initials: DF
authors.lastname: Ward
mesh_terms: D000328:Adult; D001510:Bed Rest; D003894:Deamino Arginine Vasopressin / Q000494:pharmacology* / Q000627:therapeutic use; D005440:Fluid Therapy; D018475:Head-Down Tilt / Q000502:physiology*; D006801:Humans; D007024:Hypotension, Orthostatic / Q000517:prevention & control*; D008150:Lower Body Negative Pressure; D010953:Plasma Volume / Q000187:drug effects; D012076:Renal Agents / Q000494:pharmacology* / Q000627:therapeutic use; D012965:Sodium Chloride / Q000494:pharmacology* / Q000627:therapeutic use; D014556:Urine / Q000502:physiology; D018544:Weightlessness Countermeasures
chemical_list: D012076:Renal Agents; D012965:Sodium Chloride; D003894:Deamino Arginine Vasopressin