Skeletal muscle collagen type i and iii mrna, prolyl 4-hydroxylase
and collagen in hypobaric exposed and trained rats.
Perhonen, Merja, Xiaoyan Han, Wei Wang, Jarmo Karpakka, and Timo E. S.
Takala.
Department of Physiology, University of Oulu, Kajaanintie 52 A,
FIN-90220 Oulu, Finland, Deaconess Institute of Oulu, Isokatu 47,
FIN-90100 Oulu, Finland and Department of Biology of Physical
Activity, University of Jyv[umlaut]askyl[umlaut]a, PB 35, FIN-40351
Jyv[umlaut]askyl[umlaut]a, Finland
APStracts 3:0072A, 1996.
Perhonen, M., X. Han, W. Wang, J. Karpakka and T.E.S. Takala. Skeletal
muscle collagen type I and III mRNA, prolyl 4-hydroxylase and
collagen in hypobaric exposed and trained rats. Skeletal muscle
collagen expression was studied in normobaric sedentary (NS) and
trained (NT) and hypobaric sedentary (HS) and trained (HT) rats after
experimental periods of 10, 21 and 56 days. The weights of fast
twitch extensor digitorum longus (EDL) and slow twitch soleus muscle
were increased between the experimental period of 21 and 56 days so,
that EDL weight was 57 % (p<0.01) and 36 % (p<0.05) higher
in 56HS and in 56HT, respectively, than in 56NS. Soleus muscle weight
was higher in 56HS (61 %, p<0.01) and in 56HT (27%, p<0.05)
than in 56NT. In EDL muscle collagen type I mRNA level was lower in
56HT than in 56NS (36%, p<0.05) and 56NT (44%, p<0.01). In
56HT collagen type III mRNA level was 39% (p<0.01) and 42%
(p<0.05) lower than in 56NS and 56HS, respectively. In soleus
muscle prolyl 4-hydroxylase (PH) activity was greater (p<0.05)
in 56NT, 56HS and 56HT than in 56NS. Total hydroxyproline content in
EDL muscle was increased in 56HS and 56HT and in soleus muscle of the
56HS. In conclusion, although collagen type I and III mRNA levels in
EDL muscle decreased in 56HT, the PH data suggest unchanged synthesis
of total collagen. Exposure to hypobaric condition as such, its
combination to endurance training as well as training in normobaric
condition increased prolyl 4-hydroxylation capacity in soleus muscle,
which may indicate respective change in collagen synthesis rate.
Received 5 September 1995; accepted in final form 24 January
1996.
APS Manuscript Number A955-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 8 February 96