title: Acetylcholine induces vasoconstriction in the microcirculation of cardiomyopathic hamsters: reversal by L-arginine.
abstract: The goal of this study was to determine whether endothelium-dependent responses of the microcirculation are altered during cardiomyopathy. We examined in vivo responses of cheek pouch arterioles to an endothelium-dependent agonist (acetylcholine) and an endothelium-independent agonist (nitroglycerin) in normal and in cardiomyopathic hamsters. In normal hamsters, acetylcholine produced dose-related dilatation of arterioles. In contrast, acetylcholine produced constriction of arterioles in cardiomyopathic hamsters. Nitroglycerin produced similar dose-related dilatation in normal and cardiomyopathic hamsters. We also examined whether impaired responses to acetylcholine in cardiomyopathic hamsters were related to an alteration in the L-arginine/nitric oxide pathway. We found that L-arginine (100 microM) restored endothelium-dependent vasodilatation to acetylcholine in cardiomyopathic hamsters. Thus, cardiomyopathy impairs endothelium-dependent responses of the microcirculation which is reversed by L-arginine.
authors.affiliation: Department of Physiology, University of Nebraska Medical Center, Omaha 68198.
authors.forename: W G
authors.initials: WG
authors.lastname: Mayhan
authors.forename: I
authors.initials: I
authors.lastname: Rubinstein
mesh_terms: D000109:Acetylcholine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000818:Animals; D001120:Arginine / Q000494:pharmacology*; D001160:Arterioles / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology; D009202:Cardiomyopathies / Q000235:genetics / Q000503:physiopathology*; D002610:Cheek; D006224:Cricetinae; D008297:Male; D008647:Mesocricetus; D008833:Microcirculation / Q000187:drug effects* / Q000502:physiology / Q000503:physiopathology; D009061:Mouth Mucosa / Q000098:blood supply*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology / Q000503:physiopathology; D005996:Nitroglycerin / Q000494:pharmacology; D014662:Vasoconstrictor Agents / Q000037:antagonists & inhibitors / Q000494:pharmacology*
chemical_list: D014662:Vasoconstrictor Agents; D001120:Arginine; D005996:Nitroglycerin; D000109:Acetylcholine