Changes in dietary protein intake fail to prevent decrease in
muscle growth induced by severe hypoxia in rats.
Bigard, A. X., Ph. Douce, D. Merino, F. Lienhard, and C. Y. Guezennec.
D[acute]epartement de Physiologie Syst[acute]emique, Centre
d'Etudes et de Recherches de M[acute]edecine A[acute]erospatiale, BP
73, 91223 Br[acute]etigny sur Orge Cedex, FRANCE, Tel : (011)-33-1
-69.88.33.56, Fax : (011)-33-1-69.88.33.02
APStracts 2:0399A, 1995.
Muscle growth, fiber size, muscle and liver glycogen, plasma hormones,
and muscle glutamine concentration were evaluated in rats chronically
exposed (26 days) to hypobaric conditions (HA; 6,000 m), and fed
diets of varying protein concentrations (10, 20, or 40 g protein/100g
of dry matter, LP, MP, and HP, respectively). Values were compared to
those measured in animals maintained under normobaric conditions,
either fed ad libitum (SL groups) or pair-fed equivalent quantities
of food consumed by HA animals (PF groups). There was marked anorexia
in response to HA exposure, for all protein diets (P<0.001). A
specific effect of hypoxia on the decrease in muscle growth has been
identified by comparison of muscle weight-to-body weight values
between HA and PF groups (P<0.05 for all dietary protein
levels). Plasma insulin concentrations were lower in HA than in SL
and PF rats (P<0.05). Liver glycogen was significantly decreased
by exposure to HA (P<0.001), and high dietary protein content
(P<0.005). Hypoxia per se and decreased food intake had additive
effects on soleus muscle glycogen concentrations. An increase in
muscle glutamine was observed in rats fed the LP diet in comparison
with the MP diet, especially in SL and PF groups (P<0.05). These
results clearly demonstrate that 1) hypobaric hypoxia per se
decreases growth rate in rats and 2) increasing the dietary protein
intakes in rat had no effect on the depression of muscle growth
related to high altitude, but had deleterious effects on glycogen
deposition in liver and fast muscle.
Received 20 December 1994; accepted in final form 5 September
1995.
APS Manuscript Number A1289-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 September 1995.