Orall-arginine supplementation has no effect on cardiovascular responses to lower body negative pressure in man

Abstract

L-arginine is the physiological precursor of nitric oxide, which is the major endothelium-derived relaxing factor, a potent vasodilator. This study examined the cardiovascular responses to application of incremental levels (-10, -20 and -40 mmHg) of lower body negative pressure (LBNP) in ten normal male subjects, after 1 and 7 days administration of placebo or L-arginine. It was hypothesized that L-arginine may attenuate the vasoconstrictor response elicited by application of LBNP. Placebo administration had no effect on any responses to LBNP. L-arginine administration had no significant effect on mean arterial blood pressure either after 1 day, or after 7 days. After both 1 and 7 days L-arginine ingestion, forearm blood flow (FBF) and forearm vascular conductance (FVC) were significantly lower than before L-arginine ingestion (p < 0.01), but were not significantly different from after placebo ingestion. The magnitude of the changes in FBF and FVC, induced by application of LBNP, were not different under any conditions. These findings suggest that L-arginine supplementation in healthy subjects, either acutely or chronically, has no significant effect on peripheral haemodynamics, or on reflex responses to LBNP.