Catecholamines inhibit Ca(2+)-dependent proteolysis in rat skeletal muscle through beta(2)-adrenoceptors and cAMP |
| |
Authors: | Navegantes L C Resano N M Migliorini R H Kettelhut IC |
| |
Institution: | Department of Physiology and Biochemistry, School of Medicine, University of S?o Paulo, Ribeir?o Preto, 14049-900 S?o Paulo, Brazil. |
| |
Abstract: | Overall proteolysis and the activity of skeletal muscle proteolytic systems were investigated in rats 1, 2, or 4 days after adrenodemedullation. Adrenodemedullation reduced plasma epinephrine by 95% and norepinephrine by 35% but did not affect muscle norepinephrine content. In soleus and extensor digitorum longus (EDL) muscles, rates of overall proteolysis increased by 15-20% by 2 days after surgery but returned to normal levels after 4 days. The rise in rates of protein degradation was accompanied by an increased activity of Ca(2+)-dependent proteolysis in both muscles, with no significant change in the activity of lysosomal and ATP-dependent proteolytic systems. In vitro rates of Ca(2+)-dependent proteolysis in soleus and EDL from normal rats decreased by ~35% in the presence of either 10(-5) M clenbuterol, a beta(2)-adrenergic agonist, or epinephrine or norepinephrine. In the presence of dibutyryl cAMP, proteolysis was reduced by 62% in soleus and 34% in EDL. The data suggest that catecholamines secreted by the adrenal medulla exert an inhibitory control of Ca(2+)-dependent proteolysis in rat skeletal muscle, mediated by beta(2)-adrenoceptors, with the participation of a cAMP-dependent pathway. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|