The aim was to determine the effects of enhanced availability of branched-chain amino acids (BCAAs; leucine, isoleucine, and valine) on ammonia detoxification to glutamine (GLN) and protein metabolism in two types of skeletal muscle under hyperammonemic conditions. Isolated soleus (SOL, slow-twitch) and extensor digitorum longus (EDL, fast-twitch) muscles from the left leg of white rats were incubated in a medium with 1 mM ammonia (NH3 group), BCAAs at four times the concentration of the controls (BCAA group) or high levels of both ammonia and BCAA (NH3 + BCAA group). The muscles from the right leg were incubated in basal medium and served as paired controls. L-[1-14C]leucine was used to estimate protein synthesis and leucine oxidation, and 3-methylhistidine release was used to evaluate myofibrillar protein breakdown. We observed decreased protein synthesis and glutamate and α-ketoglutarate (α-KG) levels and increased leucine oxidation, GLN levels, and GLN release into medium in muscles in NH3 group. Increased leucine oxidation, release of branched-chain keto acids and GLN into incubation medium, and protein synthesis in EDL were observed in muscles in the BCAA group. The addition of BCAAs to medium eliminated the adverse effects of ammonia on protein synthesis and adjusted the decrease in α-KG found in the NH3 group. We conclude that (i) high levels of ammonia impair protein synthesis, activate BCAA catabolism, enhance GLN synthesis, and decrease glutamate and α-KG levels and (ii) increased BCAA availability enhances GLN release from muscles and attenuates the adverse effects of ammonia on protein synthesis and decrease in α-KG.

• MeSH
• amoniak otrava   MeSH
• citrátový cyklus účinky léků   MeSH
• glutamin agonisté   metabolismus   MeSH
• hyperamonemie enzymologie   metabolismus   patofyziologie   MeSH
• jaterní cirhóza etiologie   metabolismus   MeSH
• kyseliny ketoglutarové metabolismus   MeSH
• methylhistidiny metabolismus   MeSH
• orgánová specificita MeSH
• osmolární koncentrace MeSH
• oxidace-redukce MeSH
• potkani Wistar MeSH
• proteolýza účinky léků   MeSH
• proteosyntéza účinky léků   MeSH
• radioizotopy uhlíku MeSH
• svalová vlákna typu I účinky léků   enzymologie   metabolismus   MeSH
• svalová vlákna typu II účinky léků   enzymologie   metabolismus   MeSH
• svalové proteiny genetika   metabolismus   MeSH
• techniky in vitro MeSH
• větvené aminokyseliny metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH