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Cardiovascular and Valsalva responses during parabolic flight
T T Schlegel1, E W Benavides, D C Barker
1Life Sciences Research Laboratories, National Aeronautics and Space Administration, Johnson Space Center,, Texas 77058, USA.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|November 6, 1998
Summary
Cardiovascular responses to parabolic flight show altered blood pressure regulation. Heart rate increases, but vascular resistance responses are delayed in microgravity, suggesting modified baroreflex control.
Area of Science:
- Cardiovascular Physiology
- Gravitational Biology
- Human Physiology
Background:
- Parabolic flight induces acute changes in gravity, simulating microgravity and hypergravity.
- Understanding cardiovascular adaptation to altered gravity is crucial for space travel and terrestrial research.
- The Valsalva maneuver is a standard tool for assessing autonomic cardiovascular reflexes.
Purpose of the Study:
- To investigate integrated cardiovascular responses during parabolic flight.
- To evaluate cardiovascular adjustments during quiet seated conditions and Valsalva maneuvers.
- To analyze the effects of microgravity and hypergravity on arterial pressure and vascular resistance.
Main Methods:
- 15 human subjects underwent parabolic flight.
- Cardiovascular parameters were measured during quiet seated conditions.
- Subjects performed controlled Valsalva maneuvers during different gravitational phases.
Main Results:
- Mean arterial pressure initially increased then decreased in sustained microgravity.
- Reflexive heart rate increased, but total vascular resistance responses were delayed.
- Valsalva maneuver responses were accentuated in hypergravity compared to microgravity.
Conclusions:
- Arterial baroreflex control of vascular resistance may be altered by microgravity and hypergravity.
- Cardiopulmonary, vestibular, and other receptor activities likely modify baroreflex function.
- This study provides the first systematic evaluation of cardiovascular changes during parabolic flight.