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Respiratory modulation of human autonomic rhythmsWe studied the influence of three types of breathing [spontaneous, frequency controlled (0.25 Hz), and hyperventilation with 100% oxygen] and apnea on R-R interval, photoplethysmographic arterial pressure, and muscle sympathetic rhythms in nine healthy young adults. We integrated fast Fourier transform power spectra over low (0.05-0.15 Hz) and respiratory (0.15-0.3 Hz) frequencies; estimated vagal baroreceptor-cardiac reflex gain at low frequencies with cross-spectral techniques; and used partial coherence analysis to remove the influence of breathing from the R-R interval, systolic pressure, and muscle sympathetic nerve spectra. Coherence among signals varied as functions of both frequency and time. Partialization abolished the coherence among these signals at respiratory but not at low frequencies. The mode of breathing did not influence low-frequency oscillations, and they persisted during apnea. Our study documents the independence of low-frequency rhythms from respiratory activity and suggests that the close correlations that may exist among arterial pressures, R-R intervals, and muscle sympathetic nerve activity at respiratory frequencies result from the influence of respiration on these measures rather than from arterial baroreflex physiology. Most importantly, our results indicate that correlations among autonomic and hemodynamic rhythms vary over time and frequency, and, thus, are facultative rather than fixed.
Document ID
20040112439
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Badra, L. J.
(Hunter Holmes McGuire Department of Veterans Affairs Medical Center and Medical College of Virginia at Virginia Commonwealth University Richmond, Virginia 23249, United States)
Cooke, W. H.
Hoag, J. B.
Crossman, A. A.
Kuusela, T. A.
Tahvanainen, K. U.
Eckberg, D. L.
Date Acquired
August 21, 2013
Publication Date
June 1, 2001
Publication Information
Publication: American journal of physiology. Heart and circulatory physiology
Volume: 280
Issue: 6
ISSN: 0363-6135
Subject Category
Aerospace Medicine
Funding Number(s)
CONTRACT_GRANT: HL-22296
CONTRACT_GRANT: UO1HL-56417
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
Clinical Trial
NASA Discipline Cardiopulmonary

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