title: Oral L-arginine improves hemodynamic responses to stress and reduces plasma homocysteine in hypercholesterolemic men.
abstract: When administered intravenously, L-arginine substantially reduces blood pressure (BP) and peripheral vascular resistance in healthy adults and in patients with vascular disease. Oral L-arginine has been shown to improve endothelial function; however, it is not clear whether oral administration has significant effects on systemic hemodynamics. In a randomized, placebo-controlled, crossover study we tested whether oral L-arginine (12 g/d for 3 wk) affected hemodynamics, glucose, insulin, or C-reactive protein in 16 middle-age men with hypercholesterolemia. After each treatment, hemodynamic variables were measured at rest and during 2 standardized stressor tasks (a simulated public-speaking task and the cold pressor). Regardless of treatment, the stressor tasks increased BP and heart rate (P < or = 0.02). Relative to placebo, L-arginine changed cardiac output (-0.4 L/m), diastolic BP (-1.9 mm Hg), pre-ejection period (+3.4 ms), and plasma homocysteine (-2.0 micromol/L) (P < or = 0.03). The change in plasma L-arginine was inversely correlated with the change in plasma homocysteine (r = -0.57, P = 0.03). Contrary to the results of previous studies of L-arginine administered intravenously, oral administration did not affect total peripheral resistance or plasma insulin. Oral L-arginine also did not affect plasma glucose, C-reactive protein, or lipids. This pattern of findings is consistent with the hypothesis that oral L-arginine reduces BP. This study is the first to describe a hemodynamic mechanism for the hypotensive effect of oral L-arginine and the first to show substantial reductions in homocysteine with oral administration.
authors.affiliation: Department of Biobehavioral Health at Pennsylvania State University, University Park, PA 16802, USA. sgw2@psu.edu
authors.forename: Sheila G
authors.initials: SG
authors.lastname: West
authors.forename: Andrea
authors.initials: A
authors.lastname: Likos-Krick
authors.forename: Peter
authors.initials: P
authors.lastname: Brown
authors.forename: François
authors.initials: F
authors.lastname: Mariotti
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D001120:Arginine / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects*; D019587:Dietary Supplements; D004311:Double-Blind Method; D006339:Heart Rate / Q000187:drug effects; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D006937:Hypercholesterolemia / Q000097:blood*; D008297:Male; D008875:Middle Aged; D013312:Stress, Physiological / Q000503:physiopathology*
chemical_list: D006710:Homocysteine; D001120:Arginine