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Beta-Adrenergic Receptor Population is Up-Regulated by Increased Cyclic Amp Concentration in Chicken Skeletal Muscle Cells in CultureSkeletal muscle hypertrophy is promoted in vivo by administration of beta-drenergic receptor (bAR) agonists. Chicken skeletal muscle cells were treated with 1 (mu)M isoproterenol, a strong bAR agonist, between days 7 and 10 in culture. bAR population increased by approximately 40% during this treatment; however, the ability of the cells to synthesize cyclic AMP (cAMP) was diminished by two-fold. The quantity of myosin heavy chain (MHC) was not affected. To understand further the relationship between intracellular cAMP levels, bAR population, and muscle protein accumulation, intracellular cAMP levels were artificially elevated by treatment with 0-10 uM forskolin for up to three days. The basal concentration of CAMP in forskolin-treated cells increased up to 7-fold in a dose dependent manner. Increasing concentrations of forskolin also led to an increase in bAR population, with a maximum increase of approximately 40-60% at 10 uM forskolin. A maximum increase of 40-50% in the quantity of MHC was observed at 0.2 uM forskolin, but higher concentrations of forskolin reduced the quantity of MHC back to control levels. At 0.2 uM forskolin, intracellular levels of cAMP were higher by approximately 35%, and the (beta)AR population was higher by approximately 30%. Neither the number of muscle nuclei fused into myotubes nor the percentage of nuclei in myotubes were affected by forskolin at any of the concentrations studied.
Document ID
19990070320
Document Type
Reprint (Version printed in journal)
Authors
Young, Ronald B. (NASA Marshall Space Flight Center Huntsville, AL United States)
Bridge, Kristin Y. (NASA Marshall Space Flight Center Huntsville, AL United States)
Vaughn, Jeffrey R. (NASA Marshall Space Flight Center Huntsville, AL United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1999
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other