L-arginine supplementation prolongs duration of exercise in congestive heart failure

Background: In congestive heart failure (CHF), endothelial dysfunction may contribute to impairment of exerciseinduced vasodilatation and decreased exercise capacity. We hypothesised that administration of L-arginine, a precursor of nitric oxide (NO) and postulated antioxidant, may improve endothelium - dependent vasodilatation and exercise capacity and also exert antioxidant activity.Aims: To investigate the effect of oral supplementation with L-arginine on exercise capacity and markers of oxidative stress in patients with mild to moderate CHF.Methods: The study had a randomised double-blind cross-over design. Twenty one patients with stable NYHA II-III CHF underwent three exercise tests: initially, after oral administration of L-arginine (9 g/day for 7 days) or placebo. Blood was sampled prior to each test for plasma lipid peroxides, reduced sulphydryl groups and leukocyte oxygen free radical production.Results: We found a higher prolongation of exercise duration time after L-arginine than after placebo (99±106 vs 70±99 s,