Effects of single ingestion of arginine on mTORC1 activation in rat fast- and slow-twitch muscles

This study aimed to examine whether a single ingestion of arginine activates the mammalian target rapamycin complex 1 (mTORC1) in rat fast- and slow-twitch skeletal muscles. In first experiment, rats were orally administered (3 or 10 mmol/kg body weight) water. The plantaris, gastrocnemius, soleus muscles excised h after administration. Immunoblot analysis showed that administration with higher dose (10 mmol/kg) resulted increased phosphorylation ribosomal S6 kinase (S6K) protein only amounts cellular sensor for mTORC1 subunit (CASTOR1) expressed similar these three second plantaris arginine. binding CASTOR1 GATOR2 was not detected either muscle co-immunoprecipitation immunoblot analyses, irrespective third role nitric oxide (NO) elucidated. Treatment an inhibitor NO synthase blocked arginine-induced increase S6K phosphorylation. These results indicate is capable activating suggest activation may be mediated via NO, but CASTOR1-GATOR2 pathway.