The present study was designed to investigate whether L-arginine (Arg) supplementation in exercise affects nitric oxide (NO) synthesis in tissues and thus iron metabolism. Rats were assigned to one of four groups: EG (Exercise), SG (Sedentary), EAG (Exercise + Arg), and SAG (Sedentary + Arg). Both EG and EAG swam 2 h/day for 3 months. Both SAG and EAG received 3% Arg supplementation in their drinking water. The results showed that Arg supplementation in exercise (EAG) significantly increased nitrite and nitrate (NOx) concentration in the kidney and BMC, rather than in the liver, spleen and heart. Arg supplementation significantly increased both nonheme iron (NHI) and catalytic iron (CI) content in the kidney, to the extent that the ratio of CI/NHI or storage iron (SI)/NHI was not significantly affected, and significantly decreased NHI content and increased CI content in BMC, to the extent that SI content or SI/NHI was significantly decreased. These findings suggest that Arg supplementation in exercise, possibly through increasing NO synthesis, may change CI formation in the kidney and BMC, and affect iron storage in BMC rather than in the kidney.
"Although the physiological concentrations of L-arginine are generally sufficient to saturate endothelial nitric oxide synthase  , there is evidence that increased extracellular and plasma L-arginine levels still enhance endothelial NO production   . This phenomenon is known as the L-arginine paradox. "
[Show abstract][Hide abstract] ABSTRACT: This study examined the effects of acute supplementation with L-arginine and nitrate on running economy, endurance and sprint performance in endurance-trained athletes. In a randomised cross-over, double-blinded design we compared the effects of combined supplementation with 6 g L-arginine and 614 mg nitrate against 614 mg nitrate alone and placebo in nine male elite cross-country skiers (age 18 ± 0 years, VO2max 69.3 ± 5.8 ml·min-1·kg-1). After a 48-hour standardisation of nutrition and exercise the athletes were tested for plasma nitrate and nitrite concentrations, blood pressure, submaximal running economy at 10 km·h-1 and 14 km·h-1 at 1% incline and 180 m as well as 5-km time-trial running performances. Plasma nitrite concentration following L-arginine + nitrate supplementation (319 ± 54 nmol·L-1) did not differ from nitrate alone (328 ± 107 nmol·L-1), and both were higher than placebo (149 ± 64 nmol·L-1, p < 0.01). There were no differences in physiological responses during submaximal running or in 5-km performance between treatments. The plasma nitrite concentrations indicate greater nitric oxide availability both following acute supplementation of L-arginine + nitrate and with nitrate alone compared to placebo, but no additional effect was revealed when L-arginine was added to nitrate. Still, there were no effects of supplementation on exercise economy or endurance running performance in endurance-trained cross-country skiers.
"L-Arg supplementation also can reduce skeletal muscle damage after ischemia-reperfusion  and reduce oxidative stress and inflammation after exhaustive exercise in young  and old  rats. The pharmacological effects of L-Arg supplementation are attributed to multiple factors, including increased NO production and bioactivity , decreased superoxide anions levels  and increased heme oxygenase expression . "
[Show abstract][Hide abstract] ABSTRACT: Eccentric exercise is known to disrupt sarcolemmal integrity and induce damage of skeletal muscle fibers. We hypothesized that L-arginine (L-Arg; nitric oxide synthase (NOS) substrate) supplementation prior to a single bout of eccentric exercise would diminish exercise-induced damage. In addition, we used N-nitro-L-arginine methyl ester hydrochloride (L-NAME; NOS inhibitor) to clarify the role of native NOS activity in the development of exercise-induced muscle damage. Rats were divided into four groups: non-treated control (C), downhill running with (RA) or without (R) L-Arg supplementation and downhill running with L-NAME supplementation (RN). Twenty four hours following eccentric exercise seven rats in each group were sacrificed and soleus muscles were dissected and frozen for further analysis. The remaining seven rats in each group were subjected to the exercise performance test. Our experiments showed that L-Arg supplementation prior to a single bout of eccentric exercise improved subsequent exercise performance capacity tests in RA rats when compared with R, RN and C rats by 37%, 27% and 13%, respectively. This outcome is mediated by L-Arg protection against post-exercise damage of sarcolemma (2.26- and 0.87-fold less than R and RN groups, respectively), reduced numbers of damaged muscle fibers indicated by the reduced loss of desmin content in the muscle (15% and 25% less than R and RN groups, respectively), and diminished µ-calpain mRNA up-regulation (42% and 30% less than R and RN groups, respectively). In conclusion, our study indicates that L-Arg supplementation prior to a single bout of eccentric exercise alleviates muscle fiber damage and preserves exercise performance capacity.
PLoS ONE 04/2014; 9(4):e94448. DOI:10.1371/journal.pone.0094448 · 3.23 Impact Factor
"Xiao et al.  found a negative correlation between plasma NO and iron concentration under conditions of l-arginine supplementation in exercised rats, such that increases in NO levels during exercise during l-arginine supplementation were found to lead to decreased catalytic iron concentration in the liver and increases in catalytic iron concentration in the spleen. Xiao et al.  also observed changes in nonheme iron and storage iron in the tissues of rats. "
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to evaluate the influence of the intake of L-arginine alone and of L-arginine with vitamin C on mineral concentration in rats fed with a high-fat diet, and to assess the lipid glucose, insulin, and total antioxidant status (TAS) and tumor necrosis factor (TNF) alpha serum levels that result. Wistar rats were assigned to groups fed with either a standard control diet (C), a diet high in fat (FD), a diet high in fat with L-arginine, or a diet high in fat with L-arginine and vitamin C. After 6 weeks, the length and weight of the rats were measured, and the animals were euthanized. The liver, spleen, kidneys, pancreas, heart, and gonads were collected, as were blood samples. The total serum cholesterol, triglyceride, fasting glucose, insulin, TAS, and TNF alpha levels were measured. The tissue calcium, magnesium, iron, zinc, and copper concentrations were determined. It was found that L-arginine supplementation diminished the effect of the modified diet on the concentration of iron in the liver and spleen and of copper in heart. At the same time, it was observed that L-arginine supplementation reduced the effect of the high-fat diet on insulin, TNF alpha, and TAS. The combination of L-arginine and vitamin C produced a similar effect on the mineral levels in the tissues as did L-arginine used alone. Moreover, positive correlations between serum insulin and iron in the liver, between TNF alpha and iron in the liver, and between TNF alpha and copper in the heart were observed. The level of TAS in serum was inversely correlated with the copper level in the heart and the iron level in the liver. We concluded that the beneficial influence of L-arginine on insulin, TAS, and TNF alpha serum level is associated with changes in the iron and copper status in rats fed with a high-fat diet. No synergistic effect of L-arginine and vitamin C in the biochemical parameters or in the mineral status in rats fed with the modified diet was observed.
Biological trace element research 12/2013; 157(1). DOI:10.1007/s12011-013-9867-5 · 1.75 Impact Factor
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