Bone changes in 6-month old rats after head-down suspension and a
reambulation period.
Vico, Laurence, Sandrine Bourrin, Jean Michel Very, Malgorzata
Radziszowska, Philippe Collet, Christian Alexandre.
Laboratoire de Biologie du Tissu Osseux, Facult[acute]e de
M[acute]edecine, Saint Etienne 42023, France
APStracts 2:0342A, 1995.
In mature rats experiencing 14-day head-down suspension or 14-day
head-down suspension followed by 28-day reambulation, hindlimb long
bones, humerus and skull were removed for determination of
morphometry, bone mineral content and density (BMC, BMD) using dual
-energy X-ray absorptiometry, dry and ash weights and calcium content.
Bones of animals belonging to control groups (sacrificed at day 0, 14
and 42) have their own maturation rate. The body weights of suspended
animals were lower than those of the controls. Suspension does not
appear to impair the long bone elongation rate. However the tibia of
suspended rats exhibited a lower calcium content, ash weight, BMC and
BMD. Similar trends were observed in the femur. In the humerus, no
significant change was observed. In the skull, values of suspended
rats were similar to those of controls. At the end of the
reambulation period, body weights showed no difference between
control and experimental animals. The bone alterations were not
completely reversible when compared to their respective controls. In
the tibia, BMC and BMD were always decreased. In the femur, trends
toward low values were still visible. The skull showed a decrease in
BMC, ash and dry weights. This unexpected finding suggested the
importance of a rapid decrease in cephalad fluid shift at the time of
desuspension. Finally, we showed that DEXA measurement is
sufficiently accurate to detect inter-group differences.
Received 9 May 1994; accepted in final form 6 June 1995.
APS Manuscript Number A435-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 10 August 1995.