Anabolic actions of a mixed beta-adrenergic agonist on nitrogen retention and protein turnover.
Subcutaneous administration of a mixed beta-agonist induced increases in muscle (+13%) and heart (+17%) weights, which were accompanied by a reduction in back (-13%) and perirenal (-27%) fat stores in young male rats, while no changes in liver were observed. The values of nitrogen retention (mg/day) were significantly higher in the beta-agonist treated animals (+16%) as well as those of muscle DNA content (+8%). On the other hand, no statistically significant changes in muscle protein synthetic activity (g protein synthetized/g RNA) were detected (control: 13.4 vs treated: 14.6), while muscle proteolytic activity was decreased (-9%) in those rats administered with the repartitioning agent. In this context, it is suggested that the anabolic effect of metaproterenol should be attributed to a reduction in muscle protein degradation rather than to changes in protein synthesis.
Martinez
J A
JA
Department of Physiology and Nutrition, University of Navarra, Pamplona, Spain.
Portillo
M P
MP
Larralde
J
J
D000273:Adipose Tissue / Q000033:anatomy & histology; D000818:Animals; D004247:DNA / Q000378:metabolism; D006321:Heart / Q000033:anatomy & histology; D008297:Male; D009921:Metaproterenol / Q000494:pharmacology*; D009124:Muscle Proteins / Q000096:biosynthesis / Q000378:metabolism*; D009132:Muscles / Q000033:anatomy & histology; D009584:Nitrogen / Q000378:metabolism*; D009929:Organ Size / Q000187:drug effects; D012313:RNA / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D009124:Muscle Proteins; D009921:Metaproterenol; D012313:RNA; D004247:DNA; D009584:Nitrogen