AbstractPurpose: Diminished vascular function is a primary cardiovascular risk of spaceflight identified in the 2004 NASA Bioastronautics Critical Path Roadmap based on: (1) structural and functional alterations in arterial vessels of animals undergoing hindlimb unloading and; (2) lower peripheral vascular resistance (PVR) in astronauts who became presyncopal after spaceflight.Methods: We conducted a critical review of published data obtained from spaceflight and relevant ground-based microgravity simulations in an effort to interpret the meaning of altered responses in PVR and their relationship to postflight presyncope.Results: Presyncope reported in astronauts on landing day was associated with lower peripheral resistance. However, non-presyncopal astronauts demonstrated significantly elevated vascular resistance in the upright posture after compared with before spaceflight. Results from both space and ground experiments suggest that preflight maximal vasoconstrictor capacity is inherently lower in presyncopal astronauts, but unaltered by spaceflight.Conclusions: Vasoconstrictor reserve is associated with lower blood volume adaptation to microgravity. Rather than reduced vascular function, low inherent maximal vasoconstrictor capacity and reduced vasoconstrictor reserve secondary to decreased circulating vascular volume explain lower peripheral vascular resistance in astronauts who experience presyncopal episodes on landing day.


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    Title :

    Vascular functions in humans following cardiovascular adaptations to spaceflight


    Contributors:

    Published in:

    Acta Astronautica ; 60 , 4-7 ; 259-266


    Publication date :

    2006-01-01


    Size :

    8 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English





    Vascular functions in humans following cardiovascular adaptations to spaceflight

    Convertino, V. A. / Cooke, W. H. / International Academy of Astronautics | British Library Conference Proceedings | 2007




    Cardiovascular responses to spaceflight

    Nicogossian, A. / Pool, S. L. / Rambaut, P. C. | NTRS | 1983