CL 316,243, a selective beta(3)-adrenergic agonist, inhibits protein breakdown in rat skeletal muscle.

摘要

The in vitro effect of CL 316,243 (CL), a selective beta(3)-adrenoceptor agonist in the rate of overall proteolysis, the activity of proteolytic systems (lysosomal, Ca(2+)-dependent, ATP-dependent, and ATP-independent) and in the process of protein synthesis was investigated in rat skeletal muscles. The rate of overall proteolysis in soleus muscle from rats incubated with CL (10(-4) and 10(-5) M) or epinephrine (10(-5) M) was significantly decreased. In vitro rates of maximal activity of Ca(2+)-dependent proteolysis in soleus muscles were decreased by about 41% in the presence of 10(-5) M CL. No change was observed in the activities of the lysosomal, ATP-dependent or ATP-independent proteolytic systems. The anti-proteolytic effect of CL or epinephrine was partially prevented by 10(-5) M SR 59230A, a selective beta(3)-adrenoceptor antagonist. The increase of proteolysis induced by food deprivation in soleus was abolished by in vitro addition of 10(-5) M CL. No change in proteolysis was observed in extensor digitorum longus (EDL) muscles incubated with any concentration of the beta(3)-adrenoceptor agonist tested. Rates of protein synthesis were not affected by 10(-4) M CL neither in soleus nor EDL. The data suggest that a beta(3)-adrenoceptor-mediated inhibition of Ca(2+)-dependent proteolysis participates of the antiproteolytic effect of catecholamines in oxidative muscles.