Resumo do trabalho:
Short-term creatine supplementation decrease reactive oxygen species content and modulates contractile function in skeletal muscle
Lucas Guimarães-Ferreira; Carlos Hermano J. Pinhero; Frederico Gerlinger-Romero; Kaio F. Vitzel; Renato T. Nachbar; Rui Curi; Maria Tereza Nunes
Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo/SP – Brazil.
Exercise Metabolism Research Group, Center of Physical Education and Sports, Federal University of Espirito Santo, Vitória/ES – Brazil.
Email: lucas@cefd.ufes.br.
The effect of short-term creatine supplementation (CrS) upon contractile function and content of reactive oxygen species (ROS) in skeletal muscle was investigated. Wistar rats were supplemented with creatine (Cr; 5 g/kg BW) by gavage for 6 days. Muscle contractions were evoked in triceps surae, soleus and extensor digitorum longus (EDL) in different experiments by direct electrical stimulation (ES) of sciatic nerve in vivo. Resistance to acute fatigue of rat skeletal muscle were investigated. Soleus and EDL muscles were incubated for evaluation of ROS content using Amplex-UltraRed reagent. The analysis of expression and activity of antioxidant enzymes were performed. Direct scavenger action of Cr on superoxide radical and hydrogen peroxide was also investigated. CrS improves resistance to acute fatigue during high frequency ES, evaluated by fall in force production during sucessives isometric contractions in triceps surae (control: 23%; Cr: 6.5%), soleus (control: 27.1%; Cr: 14.9%)and EDL (control: 43.2%; Cr: 0.1%) muscles. ROS content was also decreased in soleus (by 41%) and EDL (by 33.7%) muscles from Cr-supplemented rats. CrS did not change expression and activity of antioxidant enzymes. In cell-free experiments, Cr showed a scavenger action on superoxide radical, but not in hydrogen peroxide. These results indicate that CrS decreases ROS content in skeletal muscle possibly due to a direct action of Cr on superoxide radical. This action may account to CrS effects on contractile function, which were similar to those observed when N-acetyl-cysteine, a potent antioxidant, is administered prior to ES.
