title: Nitric oxide synthesized from L-arginine regulates vascular tone in the coronary circulation of the rabbit.
abstract: 1. The role of nitric oxide (NO) in the regulation of the vascular tone of the coronary circulation of the Langendorff-perfused rabbit heart was investigated. 2. NG-monomethyl-L-arginine (L-NMMA; 10-100 microM), a specific inhibitor of NO formation from L-arginine (L-Arg), but not its D-enantiomer (D-NMMA; 100 microM) produced a dose-related, sustained increase in the coronary perfusion pressure (CPP). In addition, L-NMMA inhibited the vasodilator responses of acetylcholine (ACh), unmasking in some instances its direct vasoconstrictor effect. These effects of L-NMMA were attenuated by L-Arg. 3. L-NMMA (10 and 30 microM), but not D-NMMA (30 microM), caused a long-lasting inhibition of NO formation which was reversed by L-Arg (30 and 100 microM), but not by D-Arg (100 microM). 4. This study indicates that the formation of NO from L-Arg in the coronary circulation of the rabbit plays a role both as a regulator of vascular tone and as a mediator of the vasodilatation induced by ACh.
authors: Wellcome Research Laboratories, Beckenham, Kent.
authors: J L
authors: JL
authors: Amezcua
authors: R M
authors: RM
authors: Palmer
authors: B M
authors: BM
authors: de Souza
authors: S
authors: S
authors: Moncada
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000378:metabolism* / Q000494:pharmacology; D003326:Coronary Circulation / Q000187:drug effects*; D006321:Heart / Q000187:drug effects; D066298:In Vitro Techniques; D008163:Luminescent Measurements; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D009569:Nitric Oxide / Q000494:pharmacology*; D011817:Rabbits; D013482:Superoxide Dismutase / Q000494:pharmacology; D019323:omega-N-Methylarginine
chemical_list: D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D001120:Arginine; D013482:Superoxide Dismutase; D000109:Acetylcholine