Key result
Exercise training significantly increased SOD mRNA levels (5.43 vs 1.74) and preserved fractional shortening in post-MI rats, while L-arginine provided no additive benefit.
Why the study?
Does exercise training combined with L-arginine improve ventricular remodeling and oxidative stress in post-MI rats?
RCT
randomized
Does exercise training combined with L-arginine improve ventricular remodeling and oxidative stress in post-MI rats?
Absolute Event Rate: 5.43% vs 1.74%
Exercise training attenuates myocardial fibrosis and preserves cardiac function in post-MI rats through antioxidative effects, with no additive benefit from L-arginine.
Supports antioxidant modulation by exercise plus L-arginine post-MI in rats; leaves open translation to human therapy.
OBJECTIVE: Our aim was to characterize the changes in messenger RNA (mRNA) abundance, protein, and activity levels of the enzymatic antioxidants, superoxide dismutase (SOD), glutathione peroxidase, and catalase by exercise training combined with L-arginine after myocardial infarction (MI). METHODS: L-Arginine (1 g x kg(-1) x d(-1)) and N(G)-nitro-L-arginine methyl ester (L-NAME; 10 mg x kg(-1) x d(-1)) were administered in drinking water for 8 wk. Sprague-Dawley rats were randomized to the following groups: sham-operated control (Sham); MI sedentary (Sed); MI exercise (Ex); MI sedentary + L-arginine (Sed + LA); MI exercise + L-arginine (Ex + LA); MI sedentary + L-NAME (Sed + L-NAME); and MI exercise + L-NAME (Ex + L-NAME). RESULTS: The glutathione peroxidase, catalase, and gp91(phox) mRNA levels were comparable among all the groups. The SOD mRNA level was significantly increased in the Ex group (5.43 +/- 0.87) compared with the Sed group (1.74 +/- 0.29), whereas this effect was pronouncedly down-regulated by the L-NAME intervention (2.51 +/- 1.17, P < 0.05). The protein levels of SOD in the Sed and Ex groups were both significantly decreased with the administration of L-NAME. The protein levels of catalase were significantly higher in the Ex and Ex + LA groups than that in the Sed, Sed + LA, and L-NAME-treated groups. The collagen volume fraction was significantly lowered by the exercise and/or L-arginine treatment when compared with the Sed group. Fractional shortening was significantly preserved in the trained groups compared with their corresponding sedentary groups with or without drug treatments. However, the beneficial effect was not further improved by L-arginine treatment. CONCLUSIONS: Our results suggest that exercise training exerts antioxidative effects and attenuates myocardial fibrosis in the MI rats. These improvements, in turn, alleviate cardiac stiffness and preserve post-MI cardiac function. In addition, L-arginine appears to have no additive effect on cardiac function or expression of enzymatic antioxidants.
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Xu et al. (2010) conducted an RCT in myocardial infarction. Exercise training and L-arginine vs. Sedentary control was evaluated on SOD mRNA level. Exercise training significantly increased SOD mRNA levels (5.43 vs 1.74) and preserved fractional shortening in post-MI rats, while L-arginine provided no additive benefit.
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