Beta 2-agonist fenoterol has greater effects on contractile function of rat skeletal muscles than clenbuterol.

James G Ryall, Paul Gregorevic, David R Plant, Martin N Sillence, Gordon S Lynch

Department of Physiology, The University of Melbourne, Melbourne, Victoria 3010, Australia.

American journal of physiology. Regulatory, integrative and comparative physiology 2002 Dec

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Potential treatments for skeletal muscle wasting and weakness ideally possess both anabolic and ergogenic properties. Although the beta(2)-adrenoceptor agonist clenbuterol has well-characterized effects on skeletal muscle, less is known about the therapeutic potential of the related beta(2)-adrenoceptor agonist fenoterol. We administered an equimolar dose of either clenbuterol or fenoterol to rats for 4 wk to compare their effects on skeletal muscle and tested the hypothesis that fenoterol would produce more powerful anabolic and ergogenic effects. Clenbuterol treatment increased fiber cross-sectional area (CSA) by 6% and maximal isometric force (P(o)) by 20% in extensor digitorum longus (EDL) muscles, whereas fiber CSA in soleus muscles decreased by 3% and P(o) was unchanged, compared with untreated controls. In the EDL muscles, fenoterol treatment increased fiber CSA by 20% and increased P(o) by 12% above values achieved after clenbuterol treatment. Soleus muscles of fenoterol-treated rats exhibited a 13% increase in fiber CSA and a 17% increase in P(o) above that of clenbuterol-treated rats. These data indicate that fenoterol has greater effects on the functional properties of rat skeletal muscles than clenbuterol.

Citation

James G Ryall, Paul Gregorevic, David R Plant, Martin N Sillence, Gordon S Lynch. Beta 2-agonist fenoterol has greater effects on contractile function of rat skeletal muscles than clenbuterol. American journal of physiology. Regulatory, integrative and comparative physiology. 2002 Dec;283(6):R1386-94