title: NG-monomethyl-L-arginine causes nitric oxide synthesis in isolated arterial rings: trouble in paradise.
abstract: Arginine analogs are commonly used as inhibitors of the synthesis of endothelium-derived relaxing factor, nitric oxide. However, their effect on nitric oxide levels is rarely measured. Using a chemiluminescence assay for nitric oxide, we found that NG-monomethyl-L-arginine enhanced, rather than reduced, nitric oxide synthesis in pulmonary arterial and aortic rings. NG-monomethyl-L-arginine inhibited relaxation to the endothelium-dependent vasodilator A23187 in aortic but not pulmonary arterial rings. In contrast, N omega-nitro-L-arginine did not stimulate nitric oxide synthesis and it inhibited relaxation to A23187 in all rings. We conclude that NG-monomethyl-L-arginine is a partial agonist for nitric oxide synthesis.
authors.affiliation: Division of Cardiology, Veterans Administration Medical Center, Minneapolis, Minnesota.
authors.forename: S L
authors.initials: SL
authors.lastname: Archer
authors.forename: V
authors.initials: V
authors.lastname: Hampl
mesh_terms: D000818:Animals; D001012:Aorta, Abdominal / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000502:physiology; D066298:In Vitro Techniques; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D009569:Nitric Oxide / Q000378:metabolism*; D019335:Nitroarginine; D010656:Phenylephrine / Q000494:pharmacology; D011651:Pulmonary Artery / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects; D019323:omega-N-Methylarginine
chemical_list: D010656:Phenylephrine; D019335:Nitroarginine; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D000001:Calcimycin; D001120:Arginine