Spectral indices of cardiovascular adaptations to short-term simulated microgravity exposure

We investigated the effects of exposure to microgravity on the baseline autonomic balance in cardiovascular regulation using spectral analysis of cardiovascular variables measured during supine rest. Heart rate, arterial pressure, radial flow, thoracic fluid impedance and central venous pressure wer...

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Bibliographic Details
Published in:Integrative Physiological and Behavioral Science 1995-07, Vol.30 (3), p.201-214
Main Authors: Patwardhan, A. R., Evans, J. M., Berk, M., Grande, K. J., Charles, J. B., Knapp, C. F.
Format: Article
Language:English
Subjects:
Adaptation, Physiological - physiology
Adult
Aerospace Medicine
Blood Pressure - physiology
Cardiovascular Physiological Phenomena
Diuresis - physiology
Fourier Analysis
Head-Down Tilt - physiology
Heart Rate - physiology
Hemodynamics - physiology
Humans
Male
Monitoring, Physiologic - instrumentation
Parasympathetic Nervous System - physiology
Signal Processing, Computer-Assisted
Space life sciences
Sympathetic Nervous System - physiology
Water-Electrolyte Balance - physiology
Weightlessness
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Summary:We investigated the effects of exposure to microgravity on the baseline autonomic balance in cardiovascular regulation using spectral analysis of cardiovascular variables measured during supine rest. Heart rate, arterial pressure, radial flow, thoracic fluid impedance and central venous pressure were recorded from nine volunteers before and after simulated microgravity, produced by 20 hours of 6 degrees head down bedrest plus furosemide. Spectral powers increased after simulated microgravity in the low frequency region (centered at about 0.03 Hz) in arterial pressure, heart rate and radial flow, and decreased in the respiratory frequency region (centered at about 0.25 Hz) in heart rate. Reduced heart rate power in the respiratory frequency region indicates reduced parasympathetic influence on the heart. A concurrent increase in the low frequency power in arterial pressure, heart rate, and radial flow indicates increased sympathetic influence. These results suggest that the baseline autonomic balance in cardiovascular regulation is shifted towards increased sympathetic and decreased parasympathetic influence after exposure to short-term simulated microgravity.
ISSN:1053-881X
1936-3567
DOI:10.1007/BF02698574