Central and peripheral sympathetic activity in rats during recovery
from simulated weightlessness.
Fagette, Sophie, Laurence Somody, Fatiha Bouzeghrane, Jean-Marie
Cottet-Emard, Claude Gharib, and Guillemette Gauquelin.
Laboratoire de Physiologie de l'Environnement (Groupement
d'Int[acute]er[circumflex]et Public Exercice), Facult[acute]e de
M[acute]edecine Grange-Blanche, 08 avenue Rockefeller, 69373 LYON
cedex 08, France
APStracts 2:0364A, 1995.
Rats were tail suspended keeping their forelimbs weight-bearing for 14
days and then allowed to recover for a short (6h) or a long (24h)
period to assess the behaviour of the sympathetic nervous system
following weightlessness simulation. Sympathetic activity was
determined by measuring norepinephrine (NE) turnover in the brainstem
cell groups involved in central blood pressure control and in organs
playing a key role in the cardiovascular regulation (heart and
kidneys). The norepinephrine turnover (NET) was greatly reduced in
the rostral (-56% p<0.001) and caudal (-73% p<0.001) A2
nucleus of suspended rats but was unchanged in the A1, A5 and A6 cell
groups, compared with attached rats. The NET in the cardiac atria (
-34% p<0.001), ventricles (-35% p<0.001) and kidneys (-31%
p<0.001) was decreased after suspension. The central and
peripheral sympathetic activities returned to normal within 24 hours
of release from suspension, but there was hyperactivity after 6 hours
of recovery. This raises the problem of the interpreting results
obtained in animals sacrificed a few hours after return from
spaceflight.
Received 23 January 1995; accepted in final form 3 August 1995.
APS Manuscript Number A77-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 24 August 1995.