title: Contribution of endothelium-derived nitric oxide to coronary arterial distensibility: an in vivo two-dimensional intravascular ultrasound study.
abstract: Reduced epicardial coronary arterial distensibility associated with early atherosclerosis may be mediated in part by reduced nitric oxide (NO) release. To directly assess the contribution of endogenous NO to coronary arterial distensibility, we examined the effect of intracoronary N omega nitro-L-arginine methyl ester (L-NAME), an inhibitor of NO synthase, and L-arginine, its natural substrate, on the circumflex artery in seven anesthetized dogs. We also used intracoronary acetylcholine to examine the effect of pharmacologically induced NO release on coronary distensibility. Electrocardiographically gated measurements of epicardial coronary lumen area were made by a blinded observer from images obtained with a 4.3F, 30 MHz intravascular ultrasound catheter. Aortic root pressure was continuously monitored, and neither systemic arterial pressure nor pulse pressure changed significantly with intracoronary drug administration. Change in lumen area (delta LA) from end systole to end diastole was measured, and an arterial distensibility index was calculated. Delta LA increased with acetylcholine from 8.2% +/- 0.5% at baseline to 16.3% +/- 2.8% (10(-6) mol/L; p < 0.001), with increases in both end-systolic and end-diastolic lumen area and decreased delta LA to 3.1% +/- 1.3% (p < 0.01). Lumen area and delta LA were both restored to baseline by L-arginine (10(-4)). The calculated distensibility index of the epicardial coronary artery was enhanced by acetylcholine, reduced below baseline by L-NAME, and restored to baseline by L-arginine.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco.
authors.forename: K
authors.initials: K
authors.lastname: Sudhir
authors.forename: W L
authors.initials: WL
authors.lastname: Mullen
authors.forename: D
authors.initials: D
authors.lastname: Hausmann
authors.forename: P J
authors.initials: PJ
authors.lastname: Fitzgerald
authors.forename: T M
authors.initials: TM
authors.lastname: Chou
authors.forename: P G
authors.initials: PG
authors.lastname: Yock
authors.forename: K
authors.initials: K
authors.lastname: Chatterjee
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D015906:Angioplasty, Balloon, Coronary / Q000009:adverse effects; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000187:drug effects / Q000502:physiology*; D004285:Dogs; D004730:Endothelium, Vascular / Q000187:drug effects / Q000293:injuries; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000502:physiology*; D005996:Nitroglycerin / Q000494:pharmacology; D018084:Ultrasonography, Interventional / Q000379:methods*; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology
chemical_list: D009569:Nitric Oxide; D001120:Arginine; D005996:Nitroglycerin; D000109:Acetylcholine; D019331:NG-Nitroarginine Methyl Ester