The aim of this study was to evaluate the generation of reactive oxygen species (ROS) by xanthine oxidase (XO), the enzymatic antioxidant system and oxidative damage in soleus and extensor digitorum longus (EDL) muscles of growing rats fed a low-protein, high-carbohydrate (LPHC; 6% protein, 74% carbohydrate) diet for 15 days. The LPHC diet increased the total antioxidant capacity by 45% and the activities of glutathione peroxidase (GPx), glutathione reductase and catalase in the soleus muscles. There was an increase in the carbonylated proteins with no increase thiobarbituric acid reactive substances (TBARS), although the XO activity had increased 20%. In EDL muscles, the LPHC diet increased XO activity by 66% and the TBARS levels by 80%, and only GPx had its activity increased. These results suggest that the enzymatic antioxidant system of the soleus muscle has a better response to the increase of ROS production stimulated by LPHC diet.
Keywords: Low-protein high-carbohydrate diet; antioxidant enzymes; oxidative stress; skeletal muscle; xanthine oxidase.