title: Responsiveness of Coronary Arteries to Nitroglycerin under Hypoxia: The Importance of the Endothelium.
abstract: OBJECTIVE
  Nitroglycerin is widely used as a coronary vasodilator in the treatment of ischemic heart diseases. This study investigated the influence of hypoxia on nitroglycerin-induced relaxation in endothelium-intact and -denuded rabbit, monkey, and porcine coronary arteries.
  
  
  METHODS
  Helically cut strips of coronary arteries were suspended in organ chambers, and isometric tension was recorded.
  
  
  RESULTS
  Nitroglycerin concentration dependently relaxed endothelium-intact rabbit coronary arteries, which were not different under normoxic and hypoxic conditions. On the other hand, nitroglycerin-induced relaxation of endothelium-denuded arteries was significantly attenuated by hypoxia. Similarly, the relaxant response of endothelium-intact monkey coronary arteries to nitroglycerin was not affected by hypoxia, whereas that of endothelium-denuded arteries was impaired. As is the case with rabbit and monkey coronary arteries, exposure to hypoxia resulted in impaired relaxation by nitroglycerin in endothelium-denuded but not endothelium-intact porcine coronary arteries.
  
  
  CONCLUSIONS
  These findings suggest that coronary endothelium plays a pivotal role in preventing the hypoxia-induced impairment of nitroglycerin responsiveness, regardless of the animal species.
authors.affiliation: Department of Pharmacology, Shiga University of Medical Science, Otsu, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Tawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Shimosato
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sakonjo
authors.forename: Tomio
authors.initials: T
authors.lastname: Okamura
mesh_terms: D000818:Animals; D003331:Coronary Vessels / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000502:physiology*; D005260:Female; D000860:Hypoxia / Q000503:physiopathology*; D066298:In Vitro Techniques; D008251:Macaca; D008297:Male; D005996:Nitroglycerin / Q000494:pharmacology*; D011817:Rabbits; D013552:Swine; D014664:Vasodilation / Q000187:drug effects* / Q000502:physiology*
chemical_list: D005996:Nitroglycerin