Background: Reduced availability of nitric oxide leads to dysfunction of endothelium which plays an important role in the development of cardiovascular diseases.
Objective: The aim of the present study was to determine whether the dietary supplement L-arginine improves the endothelial function of microvessels by increasing nitric oxide production.
Methods: We undertook experiments on 51 healthy male volunteers, divided into 4 groups based on their age and physical activity since regular physical activity itself increases endothelium-dependent vasodilation. The skin laser Doppler flux was measured in the microvessels before and after the ingestion of L-arginine (0.9 g). The endothelium-dependent vasodilation was assessed by acetylcholine iontophoresis and the endothelium-independent vasodilation by sodium nitroprusside iontophoresis. In addition, we measured endothelium-dependent and endothelium-independent vasodilation in 81 healthy subjects divided into four age groups.
Results: After the ingestion of L-arginine, the endothelium-dependent vasodilation in the young trained subjects increased (paired t-test, p < 0.05), while in the other groups it remained the same. There were no differences in the endothelium-independent vasodilation after ingestion of L-arginine. With aging endothelium-independent vasodilation decreased while endothelium-dependent vasodilation remained mainly unchanged.
Conclusion: Obtained results demonstrated that a single dose of L-arginine influences endothelium-dependent vasodilation predominantly in young, trained individuals.
Keywords: L-arginine; aging; endothelium-dependent vasodilation; endothelium-independent vasodilation; laser Doppler flux; nitric oxide; physical activity; skin microcirculation.