Norepinephrine kinetics in the rat with tail-suspension-induced central hypervolemia, as a model of cardio-vascular deconditioning
Maignan, E.; Martel, E.; Safar, M.; Cuche, J.L.
Journal of Gravitational Physiology a Journal of the International Society for Gravitational Physiology 7(2): P141-P142
2000
ISSN/ISBN: 1077-9248 PMID: 12697493 Document Number: 524319
Tail-suspension (TS) in the rat represents an interesting experimental condition to mimic, on Earth, the microgravity-induced cardiovascular deconditioning although the rat's profile of response is partially different from human's. To investigate underlying pathophysiological mechanisms, we have speculated on a decreased activity of the sympathetic system, (sigma S) triggered by the increase of the central venous pressure (CVP) induced by TS. Thus a decreased activity of the sigma S could account, at least partly, for the deconditioning of the cardiovascular system. The sympathetic activity (sigma A) was evaluated through measurement of the norepinephrine (NE) kinetics in rats that were tail-suspended for either 6, 24 or 48 hours. Neither NE spillover rate nor metabolic clearance rate were changed during TS, as compared to control. Thus, TS for a short period of time in the rat is unlikely to trigger a decrease of the sigma A.