Anabolic Actions of a Mixed β-Adrenergic Agonist on Nitrogen Retention and Protein Turnover

Summary

Subcutaneous administration of a mixed β-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 β-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.

Key words

Metaproterenol (Orciprenaline) - Nitrogen Balance - Protein Synthesis - Protein Breakdown