title: Human cardiovascular response to sympathomimetic agents during head-down bed rest:  the effect of dietary sodium.
abstract: Changes in sympathoadrenal function and cardiovascular deconditioning have long been recognized as a feature of the physiological adaptation to microgravity.  The deconditioning process, coupled with altered hydration status, is thought to significantly contribute to orthostatic intolerance upon return to Earth gravity.  The cardiovascular response to stimulation by sympathomimetic agents before, during, and after exposure to simulated microgravity was determined in healthy volunteers equilibrated on normal or high sodium diets in order to further the understanding of the deconditioning process.
authors.affiliation: NASA Johnson Space Center, Houston, TX, USA.
authors.forename: W J
authors.initials: WJ
authors.lastname: Williams
authors.forename: C A
authors.initials: CA
authors.lastname: Stuart
authors.forename: S M
authors.initials: SM
authors.lastname: Fortney
authors.forename: R A
authors.initials: RA
authors.lastname: Pietrzyk
authors.forename: Y M
authors.initials: YM
authors.lastname: Chen
authors.forename: P A
authors.initials: PA
authors.lastname: Whitson
mesh_terms: D000328:Adult; D000450:Aldosterone / Q000378:metabolism; D009320:Atrial Natriuretic Factor / Q000187:drug effects; D001510:Bed Rest; D018475:Head-Down Tilt / Q000502:physiology; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D010656:Phenylephrine / Q000494:pharmacology; D012083:Renin / Q000187:drug effects; D012982:Sodium, Dietary / Q000009:adverse effects*; D013566:Sympathomimetics / Q000494:pharmacology*; D014667:Vasopressins / Q000187:drug effects; D014882:Water-Electrolyte Balance / Q000502:physiology*; D018474:Weightlessness Simulation
chemical_list: D012982:Sodium, Dietary; D013566:Sympathomimetics; D014667:Vasopressins; D010656:Phenylephrine; D000450:Aldosterone; D009320:Atrial Natriuretic Factor; D012083:Renin; D007545:Isoproterenol