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Impaired pressor response after spaceflight and bed rest: evidence for cardiovascular dysfunction
J Spaak1, P Sundblad, D Linnarsson
1Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden. jonas.spaak@fyfa.ki.se
European Journal of Applied Physiology
|August 22, 2001
Summary
Cardiovascular responses to isometric muscle action are impaired after space flight (SF) and head-down-tilt bed rest (HDT). These findings suggest neurocirculatory control and effector organ impairments contribute to cardiovascular deconditioning.
Area of Science:
- Cardiovascular Physiology
- Space Medicine
- Exercise Physiology
Background:
- Space flight (SF) and head-down-tilt bed rest (HDT) induce cardiovascular deconditioning.
- Isometric muscle actions are crucial for maintaining cardiovascular function.
Purpose of the Study:
- To investigate the impact of SF and HDT on cardiovascular responses to sustained handgrip (SHG).
- To determine if impaired pressor responses contribute to deconditioning after SF and HDT.
Main Methods:
- Six subjects underwent 120 days of -6° HDT; four subjects experienced 179-389 days of SF.
- Subjects performed SHG at 30% maximal force, with heart rate (HR) and mean arterial pressure (MAP) recorded.
- Cardiovascular responses were assessed before, during, and after HDT/SF.
Main Results:
- Post-HDT, deltaHR and deltaMAP were significantly reduced (-54% and -43%, respectively).
- Post-SF, deltaMAP was markedly reduced (-79% within 24h, -35% at 1-4 days).
- DeltaHR remained unchanged after both interventions.
Conclusions:
- Attenuated pressor responses to SHG were observed after HDT and SF.
- Impairments in neurocirculatory control and effector organs likely contribute to cardiovascular deconditioning.