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Effect of hindlimb suspension on cardiovascular responses to sympathomimetics and lower body negative pressureTo determine whether hindlimb suspension is associated with the development of cardiovascular deconditioning, male rats were studied before and after undergoing one of three treatment conditions for 9 days: (1) cage control (n = 15, CON), (2) horizontal suspension (n = 15, HOZ), and (3) head-down suspension (n = 18, HDS). Testing included lower body negative pressure administered during chloralose-urethan anesthesia and graded doses of sympathomimetic agents (norepinephrine, phenylephrine, and tyramine) administered to conscious unrestrained animals. Both HDS and HOZ were associated with a small decrease in the hypotensive response to lower body negative pressure. The HOZ group, but not the HDS group, exhibited augmented reflex tachycardia. Furthermore, both HDS and HOZ groups manifested reduced pressor responses to phenylephrine after treatment. These reductions were associated with significantly attenuated increases in mesenteric vascular resistance. However, baroreflex control of heart rate was not altered by the treatment conditions. Collectively, these results indicate that 9 days of HDS in rats does not elicit hemodynamic response patterns generally associated with cardiovascular deconditioning induced by hypogravic conditions.
Document ID
19900037344
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Overton, J. Michael
(Arizona Univ. Tucson, AZ, United States)
Tipton, Charles M.
(Arizona, University Tucson, United States)
Date Acquired
August 14, 2013
Publication Date
January 1, 1990
Publication Information
Publication: Journal of Applied Physiology
Volume: 68
ISSN: 0161-7567
Subject Category
Life Sciences (General)
Accession Number
90A24399
Funding Number(s)
CONTRACT_GRANT: NAG2-392
CONTRACT_GRANT: NIH-HL-33782-02
Distribution Limits
Public
Copyright
Other

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