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Interactive effect of hypoxia and otolith organ engagement on cardiovascular regulation in humansWe determined the interaction between the vestibulosympathetic reflex and the arterial chemoreflex in 12 healthy subjects. Subjects performed three trials in which continuous recordings of muscle sympathetic nerve activity (MSNA), mean arterial blood pressure (MAP), heart rate (HR), and arterial oxygen saturation were obtained. First, in prone subjects the otolith organs were engaged by use of head-down rotation (HDR). Second, the arterial chemoreflex was activated by inspiration of hypoxic gas (10% O2 and 90% N2) for 7 min with HDR being performed during minute 6. Third, hypoxia was repeated (15 min) with HDR being performed during minute 14. HDR [means +/- SE; increase (Delta)7 +/- 1 bursts/min and Delta50 +/- 11% for burst frequency and total MSNA, respectively; P < 0.05] and hypoxia (Delta6 +/- 2 bursts/min and Delta62 +/- 29%; P < 0.05) increased MSNA. Additionally, MSNA increased when HDR was performed during hypoxia (Delta11 +/- 2 bursts/min and Delta127 +/- 57% change from normoxia; P < 0.05). These increases in MSNA were similar to the algebraic sum of the individual increase in MSNA elicited by HDR and hypoxia (Delta13 +/- 1 bursts/min and Delta115 +/- 36%). Increases in MAP (Delta3 +/- 1 mmHg) and HR (Delta19 +/- 1 beats/min) during combined HDR and hypoxia generally were smaller (P < 0.05) than the algebraic sum of the individual responses (Delta5 +/- 1 mmHg and Delta24 +/- 2 beats/min for MAP and HR, respectively; P < 0.05). These findings indicate an additive interaction between the vestibulosympathetic reflex and arterial chemoreflex for MSNA. Therefore, it appears that MSNA outputs between the vestibulosympathetic reflex and arterial chemoreflex are independent of one another in humans.
Document ID
20040088217
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Monahan, Kevin D.
(General Clinical Research Center, Pennsylvania State University College of Medicine Hershey, Pennsylvania 17033, United States)
Ray, Chester A.
Date Acquired
August 21, 2013
Publication Date
August 1, 2002
Publication Information
Publication: Journal of applied physiology (Bethesda, Md. : 1985)
Volume: 93
Issue: 2
ISSN: 8750-7587
Subject Category
Aerospace Medicine
Funding Number(s)
CONTRACT_GRANT: HL-58503
CONTRACT_GRANT: HL-67624
CONTRACT_GRANT: M01 RR-10732
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Neuroscience
Non-NASA Center

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