Role of endothelium-derived relaxing factor in parasympathetic coronary vasodilation.
Vasodilation following the infusion of acetylcholine is due to the release of endothelium-derived relaxing factor (EDRF). However, the role of EDRF in neurogenic coronary vasodilation, when acetylcholine is released outside the vessel at the adventitial-medial junction, has not been established. The action of EDRF in parasympathetic coronary vasodilation was tested in the present study using a specific inhibitor of EDRF synthesis, nitro-L-arginine methyl ester (L-NAME). Experiments were conducted on closed-chest, alpha-chloralose-anesthetized dogs with the heart paced at a constant rate. Phentolamine and propranolol were administered to block alpha- and beta-adrenergic receptors, and ibuprofen was given to inhibit prostaglandin synthesis. Intracoronary infusion of L-NAME decreased the coronary vasodilation in response to intracoronary acetylcholine or vagal stimulation. The coronary response to the endothelium-independent vasodilator nitroglycerin was unaffected by L-NAME. These data demonstrate that L-NAME specifically inhibits coronary vasodilation caused by acetylcholine and vagal stimulation, indicating that parasympathetic coronary vasodilation is dependent on EDRF.
Broten
T P
TP
Department of Physiology and Biophysics, University of Washington, School of Medicine, Seattle 98195.
Miyashiro
J K
JK
Moncada
S
S
Feigl
E O
EO
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D003326:Coronary Circulation / Q000187:drug effects / Q000502:physiology*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000502:physiology*; D005996:Nitroglycerin / Q000494:pharmacology; D010275:Parasympathetic Nervous System / Q000502:physiology*; D014630:Vagus Nerve / Q000502:physiology; D014664:Vasodilation / Q000502:physiology*
D009569:Nitric Oxide; D001285:Atropine; D001120:Arginine; D005996:Nitroglycerin; D019331:NG-Nitroarginine Methyl Ester