Evidence for superoxide anion generation in aortas of cholesterol-fed rabbits treated with L-arginine.
The inducible form of nitric oxide synthase (iNOS) is present in advanced atherosclerotic lesions. The aim of the present paper was to compare the functionality of iNOS in rabbits fed a 0.3% cholesterol-diet for 24 weeks (Baseline), and 36 weeks, with l-arginine (l-Arg) or vehicle supplementation (Saline) for the last 12 weeks. N-iminoethyl-l-lysine (l-NIL; 10 microM), a selective inhibitor of iNOS, potentiated the contractions to phenylephrine in aortas from Baseline, Saline and l-Arg rabbits confirming the presence of a functional iNOS. In l-Arg rabbits, the contractions induced by l-NIL were less pronounced than those noted in Baseline and Saline rabbits; superoxide dismutase (150 U/ml) significantly increased the phenylephrine-induced contractions only in the l-Arg rabbits. In the presence of NADPH, aortas from l-Arg rabbits produced more superoxide anions than aortas from saline rabbits as evidenced by the lucigenin-enhanced chemiluminescence technique. In conclusion, our results show functional and biochemical evidence for an increased superoxide anion production in atherosclerotic aortas from hypercholesterolemic rabbits treated with l-Arg for 12 weeks. These data may thus help to explain the lack of beneficial effects of l-Arg on atherosclerosis progression in long-term experimental hypercholesterolemia as well as in severely atherosclerotic humans.
Simonet
Serge
S
Division of Angiology, Servier Research Institute, 11 Rue des Moulineaux, 92150 Suresnes, France.
Rupin
Alain
A
Badier-Commander
Cécile
C
Coumailleau
Sophie
S
Behr-Roussel
Delphine
D
Verbeuren
Tony J
TJ
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology; D001120:Arginine / Q000097:blood / Q000494:pharmacology*; D001161:Arteriosclerosis / Q000209:etiology / Q000378:metabolism*; D002374:Catalase / Q000494:pharmacology; D002784:Cholesterol / Q000097:blood; D002791:Cholesterol, Dietary; D003324:Coronary Artery Disease / Q000517:prevention & control; D006937:Hypercholesterolemia / Q000150:complications; D066298:In Vitro Techniques; D008163:Luminescent Measurements; D008239:Lysine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D010656:Phenylephrine / Q000009:adverse effects; D011817:Rabbits; D013481:Superoxides / Q000378:metabolism*
D002791:Cholesterol, Dietary; C090663:N(6)-(1-iminoethyl)lysine; D013481:Superoxides; D010656:Phenylephrine; D001120:Arginine; D002784:Cholesterol; D002374:Catalase; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D008239:Lysine