Molecular impact of clenbuterol and isometric strength training on rat EDL muscles.

Full Abstract

Clenbuterol, a beta2-adrenergic-receptor agonist, is known to provoke muscle hypertrophy and a slow-to-fast phenotype change. A more glycolytic phenotype should be paralleled by changes in muscle glycolytic metabolism. Two groups (n=16 for each) of 3-month-old male Wistar rats (UCL:
untrained clenbuterol, and

ECL:
exercised clenbuterol) received a chronic administration of clenbuterol (2 mg/kg body weight/day). Two other groups of animals (U:
untrained and

E:
exercised), were given a 0.9% NaCl solution instead of clenbuterol. E and ECL animals followed an 8-week progressive isometric force strength-training program. Both clenbuterol administration and training resulted in an increase in extensor digitorum longus (EDL) mass despite the fact that this muscle was indirectly mobilised during isometric force strength training. Clenbuterol and training induced a consistent slow-to-fast phenotype change without drastically increasing specific activities of glycolytic enzymes. Except for GAPDH and hexokinase, modifications in glycolytic-enzyme-specific activities were not explained by transcriptional changes. Lactate dehydrogenase activity was not affected by clenbuterol but was strongly augmented by training. In EDL of ECL rats, both treatments presented an opposite effect compensating each other. GLUT1 mRNA expression was augmented in EDL of UCL and ECL animals, whereas monocarboxylate transporter 1 mRNA amounts were decreased in EDL of UCL rats. Citrate synthase activity was reduced by clenbuterol treatment but remained unchanged in EDL of E animals. Creatine kinase activity was enhanced only by clenbuterol alone. These data show that clenbuterol-induced muscle hypertrophy and slow-to-fast phenotype changes are not associated with a glycolytic-enzyme-activity increase. They also suggest that in EDL isometric force strength training can reverse clenbuterol-induced molecular adaptations.

Learn Faster Today Improve your study skills

Author information

Author/s: Mounier, Rémi (R); Cavalié, Hélian (H); Lac, Gérard (G); Clottes, Eric (E);

Affiliation: Faculté de médecine, Laboratoire Inter-Universitaire de Biologie de l'Activité Physique et Sportive, 28 Place Henri Dunant, 63001, Clermont-Ferrand, France. remimounier(-atsign-)voila.fr

Journal and publication information

Publication Type: Journal Article

Journal: Pflügers Archiv : European journal of physiology (Pflugers Arch), published in Germany. (Language: eng)

Reference: 2007-Jan; vol 453 (issue 4) : pp 497-507

Dates: Created 2007/01/11; Completed 2007/06/11;

PMID: 17093970, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

External Links for this article (including full text providers, if available):

Click Electronic Full-text Provider Links to see options for finding the electronic full text links to this article. Note there may be a subscription or fee required for access to the full text. See our FAQ for information on finding FREE full text articles.

This article may also be located in paper journal collections available in many libraries. Use the Journal and Publication Information above to find the full article.

MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Adrenergic beta-Agonists - administration & dosage; pharmacology
Animals
Body Weight - drug effects
Citrate (si)-Synthase - genetics; metabolism
Clenbuterol - administration & dosage; pharmacology
Creatine Kinase - genetics; metabolism
Gene Expression - drug effects
Glucose Transporter Type 1 - genetics
Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating) - metabolism
Glycolysis - drug effects
Hexokinase - metabolism
Insulin-Like Growth Factor I - metabolism
Isometric Contraction - drug effects

Isometric Contraction - drug effects
Male
Monocarboxylic Acid Transporters - genetics
Muscle, Skeletal - drug effects; metabolism; physiology
Myosin Heavy Chains - metabolism
Physical Conditioning, Animal - physiology
Protein Isoforms - metabolism
RNA, Messenger - genetics; metabolism
Rats
Rats, Wistar
Receptor, IGF Type 1 - blood
Reverse Transcriptase Polymerase Chain Reaction
Symporters - genetics

Associated Chemicals: Adrenergic beta-Agonists (0) ; Glucose Transporter Type 1 (0) ; Monocarboxylic Acid Transporters (0) ; Myosin Heavy Chains (0) ; Protein Isoforms (0) ; RNA, Messenger (0) ; Slc2a1 protein, rat (0) ; Symporters (0) ; monocarboxylate transport protein 1 (0) ; Clenbuterol (37148-27-9) ; Insulin-Like Growth Factor I (67763-96-6) ; Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating) (EC 1.2.1.12) ; Citrate (si)-Synthase (EC 2.3.3.1) ; Hexokinase (EC 2.7.1.1) ; Receptor, IGF Type 1 (EC 2.7.1.112) ; Creatine Kinase (EC 2.7.3.2)

These are the highest related articles currently in the database:

See 100+ related articles.