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Altered central nervous system processing of baroreceptor input following hindlimb unloading in ratsThe effect of cardiovascular deconditioning on central nervous system processing of baroreceptor afferent activity was evaluated following 14 days of hindlimb unloading (HU). Inactin-anesthetized rats were instrumented with catheters, renal sympathetic nerve electrodes, and aortic depressor nerve electrodes for measurement of mean arterial pressure, heart rate, renal sympathetic nerve activity (RSNA), and aortic depressor nerve activity (ADNA). Baroreceptor and baroreflex functions were assessed during infusion of phenylephrine and sodium nitroprusside. Central processing of baroreceptor afferent input was evaluated by linear regression relating RSNA to ADNA. The maximum baroreflex-elicited increase in RSNA was significantly reduced in HU rats (122 +/- 3.8 vs. 144 +/- 4.9% of baseline RSNA), whereas ADNA was not altered. The slope (-0.18 +/- 0.04 vs. -0.40 +/- 0.04) and y-intercept (121 +/- 3.2 vs. 146 +/- 4.3) of the linear regression relating increases in efferent RSNA to decreases in afferent ADNA during hypotension were significantly reduced in HU rats. There were no differences during increases in arterial pressure. Results demonstrate that the attenuation in baroreflex-mediated increases in RSNA following HU is due to changes in central processing of baroreceptor afferent information rather than aortic baroreceptor function.
Document ID
20040141741
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Moffitt, J. A.
(Dalton Cardiovascular Research Center, University of Missouri Columbia, Missouri 65211, United States)
Schadt, J. C.
Hasser, E. M.
Date Acquired
August 22, 2013
Publication Date
December 1, 1999
Publication Information
Publication: The American journal of physiology
Volume: 277
Issue: 6 Pt 2
ISSN: 0002-9513
Subject Category
Aerospace Medicine
Funding Number(s)
CONTRACT_GRANT: HL-55306
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Cardiopulmonary
NASA Program Biomedical Research and Countermeasures
Non-NASA Center

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