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Indomethacin attenuates post-suspension hypotension in Sprague-Dawley ratsOrthostatic hypotension is a serious condition that is sometimes manifested in astronauts during standing postflight. These observations may be related to impairment of autonomic function and/or excessive production of endothelium-dependent relaxing factors. To evaluate the role of the cyclooxygenase inhibitor indomethacin as a countermeasure against the post-suspension reduction in mean arterial pressure (MAP), we examined the cardiovascular responses to 7-day 30 degrees tail-suspension and a subsequent 6-hr post-suspension period in conscious male Sprague-Dawley rats. Indomethacin (2 mg/kg) or saline were administered intravenously prior to release from suspension and at 2 and 4 hrs post-suspension. Direct MAP and heart rate were determined prior to suspension, daily and every 2 hrs post-suspension. During suspension, MAP did not change, in contrast, during post-suspension; it decreased compared to parallel non-suspended, untreated animals. There were no significant changes in heart rate. The reduction in MAP post-suspension was associated with significant increases in plasma prostacyclin. Indomethacin attenuated the observed post-suspension reduction in MAP and reduced plasma prostacyclin levels. Also, the baroreflex sensitivity for heart rate was modified by indomethacin--the MAP threshold for baroreflex activation was raised and the effective MAP range expanded. Thus, the post suspension reduction in mean arterial pressure may be due to overproduction of vasodilatory prostaglandins and/or other endothelium-dependent relaxing factors and alteration in baroreflex activity.
Document ID
20040088060
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Bayorh, M. A.
(Morehouse School of Medicine Atlanta, Georgia, United States)
Eatman, D.
Wang, M.
Socci, R. R.
Emmett, N.
Thierry-Palmer, M.
Date Acquired
August 21, 2013
Publication Date
December 1, 2001
Publication Information
Publication: Journal of gravitational physiology : a journal of the International Society for Gravitational Physiology
Volume: 8
Issue: 2
ISSN: 1077-9248
Subject Category
Aerospace Medicine
Funding Number(s)
CONTRACT_GRANT: NCC-9-112
CONTRACT_GRANT: S06GM08248-12
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Cardiopulmonary
Non-NASA Center

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