Norepinephrine kinetics in the rat with tail-suspension-induced central hypervolemia, as a model of cardio-vascular deconditioning.
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.
Maignan
E
E
Catecholamines Biology Res. Lab, INSERM Unit-337, Broussais Faculty of Medicine, Paris, France.
Martel
E
E
Safar
M
M
Cuche
J L
JL
D000818:Animals; D018493:Cardiovascular Deconditioning / Q000502:physiology*; D002496:Central Venous Pressure / Q000502:physiology*; D018495:Fluid Shifts / Q000502:physiology; D006339:Heart Rate; D019417:Hindlimb Suspension; D023421:Models, Animal; D009638:Norepinephrine / Q000378:metabolism / Q000493:pharmacokinetics*; D051381:Rats; D017208:Rats, Wistar; D014662:Vasoconstrictor Agents / Q000378:metabolism / Q000493:pharmacokinetics*
D014662:Vasoconstrictor Agents; D009638:Norepinephrine