Abstract
Eccentrically biased exercise has been shown to result in delayed onset of muscle damage. This process has been linked to oxidative stress mechanism. However, the effect of antioxidant supplementation on oxidative stress in the skeletal muscle after eccentrically biased exercise has not been investigated. In addition, the effect in different muscle fiber types has not been compared. PURPOSE To determine if antioxidant supplementation can influence oxidative stress markers in different fiber types of rat skeletal muscle after downhill running. METHODS Sixty-six young male Sprague-Dawley rats were pretreated with either a normal diet or an antioxidant diet (2000 mg vitamin C plus 1000 IU vitamin E/g diet) for 2 weeks. Exercised rats ran 90 minutes on a rodent treadmill at a speed of 16 m/min at −16° grade. The rats were sacrificed at before (rested), immediately, 2 hours, and 48 hours post-exercise. Concentrations of malondialdehyde (MDA), protein carbonyls (PC), total glutathione (TGSH) and oxidized glutathione (GSSG) in vastus lateralis (white fast-twitch), vastus intermedius (red fast-twitch), and soleus (slow-twitch) muscles were measured. A 2 x 4 ANOVA was used to analyze the data. RESULTS PC concentration in vastus intermedius (rested =2.46 ± 0.16 nmol/mg protein, 2hr = 3.35 ± 0.24 nmol/mg protein) and soleus (rested =3.04 ± 0.22 nmol/mg protein, 2hr = 4.22 ± 0.33 nmol/mg protein) significantly increased 36% and 39% after downhill running. No changes in MDA concentrations and glutathione status were observed. Antioxidant supplementation significantly decreased PC concentrations in both vastus intermedius and soleus muscles, but did not significantly influence muscle MDA and glutathione status. CONCLUSION These data indicate that 90 minutes of downhill running resulted in protein oxidation in red fast-twitch and slow-twitch muscles of the rats and two weeks of antioxidant pretreatment reduced protein carbonyls in these muscles. (Supported in part by Susan Stout Research Fellowship from UNC-Greensboro)
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