Gender specific effects of dexamethasone treatment on rat diaphragm
structure and function.
Prezant, D. J., M. L. Karwa, B. Richner, D. Maggiore, I. Gentry, J.
Cahill.
Department of Medicine, Pulmonary Division and the Department of
Physiology and Biophysics, Albert Einstein College of Medicine,
Montefiore Medical Center
APStracts 3:0427A, 1996.
The effects of long-term dexamethasone treatment on diaphragm muscle
were stud ied in female and male rats. Compared to pair-fed controls,
dexamethasone did not signifi cantly affect estrous cycling or peak
serum estradiol levels but testosterone levels were sig nificantly
increased in females and decreased in males. Dexamethasone
significantly re duced body and costal diaphragm weights, but to a
lesser extent in females than males. Reductions in diaphragm weight
were proportional to reductions in body weight. In females and males,
dexamethasone treatment significantly decreased diaphragm fiber (type
I and II) cross-sectional area (CSA) and the relative expression of
myosin heavy chain (MHC-2B) isoform. With the exception of type I
fiber atrophy, these changes occurred to a lesser extent in females.
Dexamethasone did not significantly affect specific forces. Dexametha
sone significantly increased twitch half-relaxation time and fatigue
resistance indexes in males but not females. In conclusion, the
effects of long-term dexamethasone treatment were gender specific,
with significantly lesser effects in females, and changes in serum
tes tosterone levels were associated with these findings.
Received 5 June 1995; accepted in final form 6 September 1996.
APS Manuscript Number A582-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 7 October 1996