title: Interaction between clenbuterol and run training: effects on exercise performance and MLC isoform content.
abstract: The purpose of this study was to determine the separate and combined effects of clenbuterol (CB) administration and interval training on running performance and myosin light-chain (MLC) isoform expression in mouse skeletal muscle. Mice were randomly assigned to one of four treatment groups: 1) control (Con), 2) exercise (Ex), 3) drug (CB), or 4) exercise + drug (Ex + CB). CB and Ex + CB mice were given CB (1.6 mg/kg) orally 4 days/wk. Ex and Ex + CB mice were trained 4 days/wk on a motorized treadmill (3 sets of 3 min, 36-40 m/min, 10-17% grade, 30-s recovery). After 8 wk of treatment, exercise conditioning increased total work performed 58% in the Ex group during a run-to-exhaustion treadmill test, whereas CB decreased total work by 25% in the CB group; in combination with exercise training, CB treatment eliminated the Ex-induced increase in work. Polyacrylamide gel electrophoresis indicated that run training, CB treatment, or a combination did not (P > 0.01) promote changes in fast and slow MLC isoforms in the soleus, gastrocnemius, or tibialis anterior muscles. Although not different from each other after 8 wk, CB and Ex + CB treatments produced significantly greater values than Con and Ex for the following variables: muscle mass (17-46%), total protein (22-50%), and myofibrillar protein (19-53%). It was concluded that CB decreases exercise performance and that the combination of Ex and CB have antagonistic effects on running performance; the two treatments do not interact to diminish the anabolic effects of CB on skeletal muscle and do not alter MLC isoform profiles.
authors.affiliation: Department of Health, Texas A&M University, College Station 77843, USA.
authors.forename: C P
authors.initials: CP
authors.lastname: Ingalls
authors.forename: W S
authors.initials: WS
authors.lastname: Barnes
authors.forename: S B
authors.initials: SB
authors.lastname: Smith
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002976:Clenbuterol / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D018482:Muscle, Skeletal / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000235:genetics*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D013997:Time Factors
chemical_list: D018995:Myosin Heavy Chains; D002976:Clenbuterol