Changes in diaphragm muscle collagen gene expression following
acute unilateral denervation.
Gosselin, Luc E., Gary C. Sieck, Ross A. Aleff, Daniel A. Martinez,
and Arthur C. Vailas.
Departments of Anesthesiology, Physiology and Biophysics, Mayo
Clinic and Foundation, Rochester, MN 55905 and Biodynamics
Laboratory, University of Wisconsin, Madison, WI 53706
APStracts 2:0244A, 1995.
The purpose of the present study was to examine the effects of acute
(three days) unilateral diaphragm DNV on: 1) levels of [alpha]1(I)
and [alpha]1(III) procollagen mRNA; 2) collagen concentration
(hydroxyproline; HYP); 3) amount of the nonreducible collagen cross
-link hydroxylysylpyridinoline (HP); and 4) the passive force-length
relationship of the muscle. The level of [alpha]1(I) and
[alpha]1(III) procollagen mRNA, HYP concentration, and amount of HP
was measured in muscle segments from the midcostal region of DNV and
intact (INT) hemidiaphragms of adult male Fischer 344 rats (250-300
gms). The in vitro passive force-length relationship of DNV and INT
hemidiaphragm was determined by lengthening and shortening the
diaphragm muscle segments from 85% to 115% of optimal length (Lo) at
a constant velocity (0.6 Lo/sec). Three days after DNV, the level of
[alpha]1(I) procollagen mRNA was increased over 15-fold in the DNV
hemidiaphragm compared with INT (P < 0.05) whereas the level of
[alpha]1(III) procollagen mRNA was increased 6-fold in the DNV
hemidiaphragm compared with INT (P < 0.05). Collagen (HYP)
concentration did not differ between groups, averaging 8.7 and 8.9
Ng/mg dry wt. for the DNV and INT hemidiaphragm respectively. In
addition, there was no difference in the amount of the mature, non
-reducible collagen cross-link HP between the DNV and INT
hemidiaphragms (0.66 vs 0.76 mole HP/mole collagen, respectively).
The amount of passive force developed during lengthening did not
differ between DNV and INT hemidiaphragms. These data indicate that
acute DNV of the hemidiaphragm is associated with an increase in the
mRNA level of the two principle fibrillar collagen phenotypes in
skeletal muscle. However, in spite of extensive muscle remodelling,
the passive force-length relationship of the DNV hemidiaphragm is
unaffected compared to the INT muscle.
Received 24 November 1994; accepted in final form 1 June 1995.
APS Manuscript Number A1193-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 July 1995.