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

The cancerogen 1,2-dimethylhydrazine (DMH), widely used in the experimental animal model of carcinogenesis, affects various organs, but its effect on muscle fibers is unknown. To evaluate the effect of 15-week DMH treatment on the fiber size and myosin heavy chain (MyHC) isoforms, which substantially determine fiber types and their contractile characteristics, pure and hybrid fiber types were immunohistochemically determined according to the MyHC isoform expression in soleus, extensor digitorum longus, gastrocnemius medialis and lateralis muscles of DMH-treated and control male Wistar rats. Whereas the size of fibers was mostly unaffected, the MyHC isoform expression was partially affected in both gastrocnemius samples, but not in the soleus and extensor digitorum longus of DMH-treated rats. The lower proportions of hybrid fiber types and especially that of type 1/2x in most gastrocnemius samples of DMH-treated rats resulted in a shift towards a single MyHC isoform expression, but the extent and pattern of the MyHC isoform shift varied across the different gastrocnemius samples. Such variable response to DMH treatment across muscles indicates that each muscle possesses its own adaptive range. These findings are essential for an accurate evaluation of skeletal muscle characteristics in DMH animal model.

• MeSH
• 1,2-dimethylhydrazin toxicita   MeSH
• karcinogeny toxicita   MeSH
• kosterní svalová vlákna účinky léků   metabolismus   patologie   MeSH
• krysa rodu rattus MeSH
• potkani Wistar MeSH
• svalová vlákna typu I účinky léků   metabolismus   patologie   MeSH
• svalová vlákna typu II účinky léků   metabolismus   patologie   MeSH
• těžké řetězce myosinu biosyntéza   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

The aim of our study was to evaluate the differences in protein and amino acid metabolism after subcutaneous turpentine administration in the soleus muscle (SOL), predominantly composed of red fibres, and the extensor digitorum longus muscle (EDL) composed of white fibres. Young rats (40-60 g) were injected subcutaneously with 0.2 ml of turpentine oil/100 g body weight (inflammation) or with the same volume of saline solution (control). Twenty-four hours later SOL and EDL were dissected and incubated in modified Krebs-Heinseleit buffer to estimate total and myofibrillar proteolysis, chymotrypsin-like activity of proteasome (CHTLA), leucine oxidation, protein synthesis and amino acid release into the medium. The data obtained demonstrate that in intact rats, all parameters measured except protein synthesis are significantly higher in SOL than in EDL. In turpentine treated animals, CHTLA increased and protein synthesis decreased significantly more in EDL. Release of leucine was inhibited significantly more in SOL. We conclude that turpentine-induced inflammation affects more CHTLA, protein synthesis and leucine release in EDL compared to SOL.

• MeSH
• financování organizované MeSH
• krysa rodu rattus MeSH
• leucin metabolismus   MeSH
• potkani Wistar MeSH
• proteasomový endopeptidasový komplex metabolismus   MeSH
• svalová vlákna typu I účinky léků   MeSH
• svalová vlákna typu II účinky léků   MeSH
• terpentýn farmakologie   MeSH
• zánět chemicky indukované   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH

• MeSH
• financování vládou MeSH
• interpretace statistických dat MeSH
• kofein farmakokinetika   MeSH
• potkani Wistar MeSH
• svalová kontrakce fyziologie   účinky léků   MeSH
• svalová vlákna typu I účinky léků   MeSH
• svalová vlákna typu II účinky léků   MeSH
• teplota MeSH
• vápníkové kanály fyziologie   účinky léků   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• srovnávací studie MeSH