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Aging attenuates the vestibulosympathetic reflex in humansBACKGROUND: The vestibular system contributes to sympathetic activation by engagement of the otolith organs. However, there is a significant loss of vestibular function with aging. Therefore, the purpose of the present study was to determine if young and older individuals differ in their cardiovascular and sympathetic responses to otolithic stimulation (ie, head-down rotation, HDR). We hypothesized that responses to otolithic stimulation would be attenuated in older adults because of morphological and physiological alterations that occur in the vestibular system with aging. METHODS AND RESULTS: Arterial blood pressure, heart rate, muscle sympathetic nerve activity (MSNA), and head rotation were measured during HDR in 11 young (26 +/- 1 years) and 11 older (64 +/- 1 years) subjects in the prone posture. Five older subjects performed head rotation (chin to chest) in the lateral decubitus position, which simulates HDR but does not alter afferent inputs from the vestibular system. MSNA responses to HDR were significantly attenuated in older as compared with young subjects (P<0.01). MSNA increased in the older subjects by only 12 +/- 5% as compared with 85 +/- 16% in the young. Furthermore, HDR elicited significant reductions in mean arterial blood pressure in older (Delta-6 +/- 1 mm Hg; P<0.01) but not young subjects (Delta1 +/- 1 mm Hg). In contrast to HDR, head rotation performed in the lateral decubitus position did not elicit hypotension. MSNA responses to baroreceptor unloading and the cold pressor test were not different between the age groups. CONCLUSIONS: These data indicate that aging attenuates the vestibulosympathetic reflex in humans and may contribute to the increased prevalence of orthostatic hypotension with age.
Document ID
20040088441
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Ray, Chester A.
(General Clinical Research Center, Pennsylvania State University College of Medicine, The Milton S. Hershey Medical Center Hershey, Pa 17033-2390, United States)
Monahan, Kevin D.
Date Acquired
August 21, 2013
Publication Date
February 26, 2002
Publication Information
Publication: Circulation
Volume: 105
Issue: 8
ISSN: 0009-7322
Subject Category
Aerospace Medicine
Funding Number(s)
CONTRACT_GRANT: M01-RR10732
CONTRACT_GRANT: HL-67624
CONTRACT_GRANT: HL-58303
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Neuroscience
Clinical Trial
Non-NASA Center

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