Contractile properties of clenbuterol-treated mdx muscle are
enhanced by low-intensity swimming.
Hayes, Alan, and David A. Williams.
Muscle and Cell Physiology Laboratory, Department of Physiology,
The University of Melbourne, Parkville, Victoria, 3052, Australia
APStracts 3:0461A, 1996.
The b2-agonist clenbuterol has potent anabolic properties in normal
and denervated muscle, and as such, may be of use in muscle wasting
diseases such as muscular dystrophy. However, potential side-effects
such as the transformation of the fiber type pool towards increased
proportions of fast-twitch fibers must be balanced with the
beneficial anabolic properties. In the present report, we clearly
show that extensor digitorum longus and soleus muscles from
dystrophic mdx mice exposed to a combination of clenbuterol and low
-intensity endurance swimming exercise did not undergo the slow- to
fast-twitch fiber transformations caused by clenbuterol
administration alone, yet increases in the force generating capacity
of the soleus (30-40%) which resulted from the clenbuterol treatment
were maintained after the swimming program. The increased sensitivity
of dystrophin-deficient dystrophic muscle to clenbuterol and low
-intensity exercise which is evident in this study may have
therapeutic implications in the treatment of muscle wasting diseases.
Received 26 March 1996; accepted in final form 18 September 1996.
APS Manuscript Number A315-6.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996