Affiliations: Institute of physiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
Correspondence:
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Corresponding author: Ziva Melik, Institute of physiology, Faculty of Medicine, University of Ljubljana, Zaloska 4, 1000 Ljubljana, Slovenia. Tel.: +386 15437500; Fax: +386 15437501; E-mail: [email protected].
Abstract: 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.
