Ractopamine increases total and myofibrillar protein synthesis in cultured rat myotubes. 1990

P T Anderson, and W G Helferich, and L C Parkhill, and R A Merkel, and W G Bergen
Department of Animal Science, Michigan State University, East Lansing 48824.

The ability of the phenethanolamine (beta-adrenergic agonist) ractopamine to stimulate cellular protein accretion and protein synthesis in cultured muscle cells was evaluated. ELC5 myoblasts (a subclone of rat L6 cells) were proliferated in culture (Dulbecco's Modified Eagle Medium plus 10% fetal bovine serum at 37 degrees C) to confluency and then allowed to differentiate to form myotubes. Myotubes were then further incubated in the presence of 10(-9), 10(-8), 10(-7), 10(-6) or 10(-5) mol/L ractopamine. A significant (p less than 0.05) response in cellular protein accretion was observed for the 10(-6) and 10(-5) concentrations when compared to 10(-8) and 10(-9) mol/L ractopamine. Ractopamine at 0 and 10(-6) mol/L was used to examine the effect of the beta agonist on [35S]methionine incorporation (protein synthesis) into total cellular protein, 43-kDa proteins and myosin heavy-chain (200 kDa) protein. Protein synthesis in response to beta agonist treatment was measured at 4, 24, 48, 72 and 96 h after ractopamine addition to the ELC5 myotubes in culture. Ractopamine (10(-6) mol/L) increased [35S]methionine incorporation (apparent protein synthesis) at 24 h (p less than 0.01), 48 h (p less than 0.05), 72 h (p less than 0.01) and 96 h (p less than 0.05) in cultured ELC5 muscle cells. Ractopamine also increased apparent protein synthesis rate of the 43-kDa proteins (p less than 0.05) and myosin heavy-chain protein (200 kDa) (p less than 0.05). These results indicate that ractopamine-enhanced ELC5 myotube protein accretion is mediated, at least in part, by stimulating cellular protein synthesis.

UI MeSH Term Description Entries
D008970 Molecular Weight The sum of the weight of all the atoms in a molecule. Molecular Weights,Weight, Molecular,Weights, Molecular
D009124 Muscle Proteins The protein constituents of muscle, the major ones being ACTINS and MYOSINS. More than a dozen accessory proteins exist including TROPONIN; TROPOMYOSIN; and DYSTROPHIN. Muscle Protein,Protein, Muscle,Proteins, Muscle
D009132 Muscles Contractile tissue that produces movement in animals. Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
D009210 Myofibrils The long cylindrical contractile organelles of STRIATED MUSCLE cells composed of ACTIN FILAMENTS; MYOSIN filaments; and other proteins organized in arrays of repeating units called SARCOMERES . Myofilaments,Myofibril,Myofilament
D009218 Myosins A diverse superfamily of proteins that function as translocating proteins. They share the common characteristics of being able to bind ACTINS and hydrolyze MgATP. Myosins generally consist of heavy chains which are involved in locomotion, and light chains which are involved in regulation. Within the structure of myosin heavy chain are three domains: the head, the neck and the tail. The head region of the heavy chain contains the actin binding domain and MgATPase domain which provides energy for locomotion. The neck region is involved in binding the light-chains. The tail region provides the anchoring point that maintains the position of the heavy chain. The superfamily of myosins is organized into structural classes based upon the type and arrangement of the subunits they contain. Myosin ATPase,ATPase, Actin-Activated,ATPase, Actomyosin,ATPase, Myosin,Actin-Activated ATPase,Actomyosin ATPase,Actomyosin Adenosinetriphosphatase,Adenosine Triphosphatase, Myosin,Adenosinetriphosphatase, Actomyosin,Adenosinetriphosphatase, Myosin,Myosin,Myosin Adenosinetriphosphatase,ATPase, Actin Activated,Actin Activated ATPase,Myosin Adenosine Triphosphatase
D010627 Phenethylamines A group of compounds that are derivatives of beta- aminoethylbenzene which is structurally and pharmacologically related to amphetamine. (From Merck Index, 11th ed) Phenylethylamines
D002455 Cell Division The fission of a CELL. It includes CYTOKINESIS, when the CYTOPLASM of a cell is divided, and CELL NUCLEUS DIVISION. M Phase,Cell Division Phase,Cell Divisions,Division Phase, Cell,Division, Cell,Divisions, Cell,M Phases,Phase, Cell Division,Phase, M,Phases, M
D002460 Cell Line Established cell cultures that have the potential to propagate indefinitely. Cell Lines,Line, Cell,Lines, Cell
D000318 Adrenergic beta-Agonists Drugs that selectively bind to and activate beta-adrenergic receptors. Adrenergic beta-Receptor Agonists,beta-Adrenergic Agonists,beta-Adrenergic Receptor Agonists,Adrenergic beta-Agonist,Adrenergic beta-Receptor Agonist,Betamimetics,Receptor Agonists, beta-Adrenergic,Receptors Agonists, Adrenergic beta,beta-Adrenergic Agonist,beta-Adrenergic Receptor Agonist,Adrenergic beta Agonist,Adrenergic beta Agonists,Adrenergic beta Receptor Agonist,Adrenergic beta Receptor Agonists,Agonist, Adrenergic beta-Receptor,Agonist, beta-Adrenergic,Agonist, beta-Adrenergic Receptor,Agonists, Adrenergic beta-Receptor,Agonists, beta-Adrenergic,Agonists, beta-Adrenergic Receptor,Receptor Agonist, beta-Adrenergic,Receptor Agonists, beta Adrenergic,beta Adrenergic Agonist,beta Adrenergic Agonists,beta Adrenergic Receptor Agonist,beta Adrenergic Receptor Agonists,beta-Agonist, Adrenergic,beta-Agonists, Adrenergic,beta-Receptor Agonist, Adrenergic,beta-Receptor Agonists, Adrenergic
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia

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