title: Chronic oral administration of beta-adrenoceptor agonist clenbuterol affects myosin heavy chain (MHC) expression in adult mouse heart.
abstract: The aim of this study was to analyze the effects of chronic administration of the beta-adrenoceptor agonist clenbuterol (2 mg/kg body weight/day for a period of 30 days) on the major contractile protein (myosin) in the left ventricular muscle of the adult mouse heart. Separation of myosin heavy chain (MHC) isoforms on 7.5 % glycerol SDS-PAGE and subsequent quantification of the gels by laser densitometry showed a 6.5-fold increase in the beta-isoform of MHC in the clenbuterol-treated group. The alpha : beta ratio of these two isoforms in the control group was 98.16+/-0.14 %: 1.83+/-0.14 %, whereas in the treated group it was 88.05+/-1.15 % : 11.95+/-1.15 %. Actomyosin ATPase activity assay demonstrated a significant (20 %) decline in ATPase activity of the tissue in the beta-agonist-treated group. These results suggest that chronic clenbuterol treatment is capable to induced the transformation of MHC isoforms increasing the slow beta-MHC isoform, which may contribute to the altered contractile mechanics of clenbuterol-treated hearts.
authors.affiliation: Department of Biosciences, Himachal Pradesh University sumer Hill, Shimla, India. snpatiyal@yahoo.co.in
authors.forename: S N
authors.initials: SN
authors.lastname: Patiyal
authors.forename: S
authors.initials: S
authors.lastname: Sharma
mesh_terms: D000284:Administration, Oral; D000318:Adrenergic beta-Agonists / Q000008:administration & dosage* / Q000494:pharmacology; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002976:Clenbuterol / Q000008:administration & dosage* / Q000494:pharmacology; D006352:Heart Ventricles / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D018995:Myosin Heavy Chains / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism; D020033:Protein Isoforms / Q000378:metabolism
chemical_list: D000318:Adrenergic beta-Agonists; D020033:Protein Isoforms; D018995:Myosin Heavy Chains; D009218:Myosins; D002976:Clenbuterol