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NOS II inhibition attenuates post-suspension hypotension in Sprague-Dawley ratsThe reduction in mean arterial pressure observed in astronauts may be related to the impairment of autonomic function and/or excessive production of endothelium-derived relaxing factors. Here, we examined the role of a nitric oxide synthase II (NOS II) inhibitor AMT (2-amino-dihydro-6-methyl-4H-1,3-thiazine) against the post-suspension reduction in mean arterial pressure (MAP) in conscious male Sprague-Dawley rats. Direct MAP and heart rate were determined prior to tail-suspension, daily during the 7-day suspension and every 2 hrs post-suspension. Prior to release from suspension and at 2 and 4 hrs post-suspension, AMT (0.1 mg/kg), or saline, were administered intravenously. During the 7-day suspension, MAP was not altered, nor were there significant changes in heart rate. The reduction in MAP post-suspension in saline-treated rats was associated with significant increases in plasma nitric oxide and prostacyclin. 2-Amino-dihydro-6-methyl4H-1,3-thiazine reduced plasma nitric oxide levels, but not those of prostacyclin, attenuated the observed post-suspension reduction in MAP and modified the baroreflex sensitivity for heart rate. Thus, the post suspension reduction in mean arterial pressure is due, in part, to overproduction of nitric oxide, via the NOS II pathway, and alteration in baroreflex activity.
Document ID
20040087829
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Eatman, D.
(Morehouse School of Medicine Atlanta, Georgia 30310-1495, United States)
Walton, M.
Socci, R. R.
Emmett, N.
Bayorh, M. A.
Date Acquired
August 21, 2013
Publication Date
January 1, 2003
Publication Information
Publication: Clinical and experimental hypertension (New York, N.Y. : 1993)
Volume: 25
Issue: 1
ISSN: 1064-1963
Subject Category
Aerospace Medicine
Funding Number(s)
CONTRACT_GRANT: S06GM08248-12
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Cardiopulmonary
Non-NASA Center

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