title: Beta 2-agonist fenoterol has greater effects on contractile function of rat skeletal muscles than clenbuterol.
abstract: 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.
authors.affiliation: Department of Physiology, The University of Melbourne, Melbourne, Victoria 3010, Australia.
authors.forename: James G
authors.initials: JG
authors.lastname: Ryall
authors.forename: Paul
authors.initials: P
authors.lastname: Gregorevic
authors.forename: David R
authors.initials: DR
authors.lastname: Plant
authors.forename: Martin N
authors.initials: MN
authors.lastname: Sillence
authors.forename: Gordon S
authors.initials: GS
authors.lastname: Lynch
mesh_terms: D000311:Adrenal Glands / Q000187:drug effects; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D002976:Clenbuterol / Q000494:pharmacology*; D005280:Fenoterol / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D018656:Muscle Fibers, Fast-Twitch / Q000187:drug effects / Q000502:physiology; D018657:Muscle Fibers, Slow-Twitch / Q000187:drug effects / Q000502:physiology; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000502:physiology; D009929:Organ Size; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000318:Adrenergic beta-Agonists; D005280:Fenoterol; D002976:Clenbuterol