Tissue protein turnover in animals treated with the mixed beta-agonist metaproterenol: influence of dose, route and pattern of administration.
beta-Adrenergic agonists have been shown to increase protein deposition as a result of changes in the balance between protein synthesis and degradation rates. The aim of this study is to investigate the effect of the treatment with the non-selective beta-adrenergic agonist, metaproterenol, on protein metabolism in rats as well as the influence of the route and pattern of administration. A short- and long-term experimental trial were carried out. After the short-term treatment with the beta-agonist (1 mg/kg), neither protein nor nucleic acids were affected in liver or gastrocnemious muscle, while cathepsin A activity, an index of protein degradation, significantly increased in muscle. However, cathepsin A activity was reduced in muscle by the oral administration during 21 days of metaproterenol (2 ppm/day), but not by the subcutaneous injections (0.1 mg/kg/day). On the other hand, RNA/DNA, an index of protein synthesis capacity, and protein/DNA, an indicator of cell size, significantly diminished in muscle after the subcutaneous long-term treatment but did not change in the liver of treated rats. Our study has demonstrated a different outcome of a mixed beta-adrenergic agonist on protein metabolism depending on the duration of the treatment and the route of administration.
Pascual
M
M
Department of Physiology and Nutrition, University of Navarra, Pamplona, Spain.
Del Barrio
A S
AS
Portillo
M P
MP
Martinez
J A
JA
Larralde
J
J
D000284:Administration, Oral; D000704:Analysis of Variance; D000818:Animals; D001835:Body Weight; D002268:Carboxypeptidases / Q000378:metabolism*; D043402:Cathepsin A; D002403:Cathepsins / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D004334:Drug Administration Schedule; D007279:Injections, Subcutaneous; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D009921:Metaproterenol / Q000008:administration & dosage / Q000494:pharmacology*; D009124:Muscle Proteins / Q000378:metabolism*; D009132:Muscles / Q000187:drug effects* / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D012313:RNA / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D009124:Muscle Proteins; D011506:Proteins; D009921:Metaproterenol; D012313:RNA; D004247:DNA; D002268:Carboxypeptidases; D002403:Cathepsins; D043402:Cathepsin A