Oral L-arginine improves endothelial dysfunction in patients with essential hypertension.
BACKGROUND
L-Arginine is a nitric oxide precursor, which augments endothelium-dependent vasodilatation in hypercholesterolemic humans and animals. Endothelium-dependent vasodilation is attenuated in patients with hypertension; however the effects of oral L-arginine on endothelial function of the conduit arteries in patients with essential hypertension have not previously been investigated.


METHODS
In a prospective randomized double blind trial, 35 patients with essential hypertension received either 6 g L-arginine (18 subjects) or placebo (17 subjects). Patients were examined for flow-mediated endothelium-dependent dilatation of the brachial artery before and 1.5 h after administration of L-arginine or placebo. At the end of the protocol the nitrate-induced, endothelium-independent vasodilatation was evaluated.


RESULTS
Two groups of L-arginine and placebo were similar regarding age, sex, blood lipids, smoking, diabetes, coronary artery disease, body mass index, intima-media thickness of the common carotid artery, clinics blood pressure and baseline brachial artery parameters. Administration of L-arginine or placebo did not change significantly heart rate, blood pressure, baseline diameter, blood flow or reactive hyperemia. L-Arginine resulted in a significant improvement of flow-mediated dilatation (1.7+/-3.4 vs. 5.9+/-5.4%, P=0.008) while placebo did not significantly change this parameter (3.0+/-2.7 vs. 3.1+/-2.2%, P=ns). The effect of L-arginine on flow-mediated dilatation was significantly different from the effect of placebo (P=0.05). L-Arginine did not significantly influence nitrate-induced dilatation (16+/-6.9 vs. 17.7+/-6.7%, P=ns).


CONCLUSIONS
Oral administration of L-arginine acutely improves endothelium-dependent, flow-mediated dilatation of the brachial artery in patients with essential hypertension. The long-term effects of L-arginine in these patients require further investigation.
Lekakis
John P
JP
Department of Clinical Therapeutics, Athens University, Alexandra Hospital, Greece. lekakisj@otenet.gr
Papathanassiou
Sotirios
S
Papaioannou
Theodoros G
TG
Papamichael
Christos M
CM
Zakopoulos
Nikos
N
Kotsis
Vassilios
V
Dagre
Anna G
AG
Stamatelopoulos
Kimon
K
Protogerou
Athanassios
A
Stamatelopoulos
Stamatios F
SF
D000284:Administration, Oral; D000328:Adult; D000368:Aged; D001120:Arginine / Q000008:administration & dosage* / Q000627:therapeutic use*; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000187:drug effects / Q000503:physiopathology; D004311:Double-Blind Method; D004730:Endothelium, Vascular / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000503:physiopathology*; D005260:Female; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology; D006801:Humans; D006973:Hypertension / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014463:Ultrasonography
D001120:Arginine