L-Arginine, a precursor of EDRF in vitro, produces pulmonary vasodilation in lambs.
There is increasing evidence that resting pulmonary vascular tone is mediated in part by the release of endothelium-derived relaxing factors (EDRF). Because L-arginine may be a precursor for EDRF synthesis, we studied the pulmonary vasodilating effects of L-arginine at rest and during pulmonary hypertension in 16 intact newborn lambs. At rest, the intravenous infusions of L-arginine (150 mg/kg) had no hemodynamic effects. However, during pulmonary hypertension induced by hypoxia or the infusion of U-46619 (a thromboxane A2 mimic), L-arginine decreased pulmonary arterial pressure by 22 and 27%, respectively (P less than 0.05). The decrease in pulmonary arterial pressure produced by L-arginine was blocked by methylene blue, a guanylate cyclase inhibitor, and augmented by Zapranast, a guanosine 3',5'-cyclic monophosphate (cGMP) phosphodiesterase inhibitor (-17.9 vs. -31.2%, P less than 0.05). In addition, L-arginine partially reversed the pulmonary hypertension induced by N omega-nitro-L-arginine, a competitive EDRF synthesis inhibitor, but D-arginine had no hemodynamic effects. This study suggests that L-arginine produces pulmonary vasodilation by increasing cGMP concentrations, supporting the in vitro hypothesis that L-arginine is a precursor for EDRF synthesis, whose availability may become rate limiting during pulmonary hypertension.
Fineman
J R
JR
Department of Pediatrics, University of California, San Francisco 94143.
Chang
R
R
Soifer
S J
SJ
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000037:antagonists & inhibitors; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006976:Hypertension, Pulmonary / Q000139:chemically induced / Q000503:physiopathology; D007536:Isomerism; D008751:Methylene Blue / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology; D009569:Nitric Oxide / Q000096:biosynthesis / Q000502:physiology*; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D011651:Pulmonary Artery / Q000187:drug effects / Q000502:physiology* / Q000503:physiopathology; D011688:Purinones / Q000494:pharmacology; D012756:Sheep; D014664:Vasodilation / Q000187:drug effects*; D019323:omega-N-Methylarginine
D011450:Prostaglandin Endoperoxides, Synthetic; D011688:Purinones; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D001120:Arginine; D015106:3',5'-Cyclic-GMP Phosphodiesterases; C011145:zaprinast; D008751:Methylene Blue