title: Central role of vascular smooth muscle hyperreactivity in coronary hyperconstriction after balloon injury in miniature pigs.
abstract: BACKGROUND
  Coronary constrictive responses to autacoids become augmented 1 week after balloon injury in our swine model. The present study aimed to elucidate the mechanisms of this effect.
  
  
  METHODS
  In 12 hypercholesterolaemic miniature pigs, the coronary constrictive response to serotonin was examined angiographically 1 week after injury. After the angiographic study, organ chamber experiments using excised coronary artery were performed to clarify whether functional changes in endothelial cells or in vascular smooth muscle cells contributed to the hyperconstriction.
  
  
  RESULTS
  The coronary constrictive response to serotonin in vivo was significantly greater at the previously injured site than at the non-injured site. The degree of the hyperconstriction at the previously injured site exceeded that predicted from a geometric theory. Histological examination demonstrated that the previously injured site was almost covered with regenerated endothelial cells. In vitro studies demonstrated that serotonin caused significantly greater contraction in coronary artery strips, whether with or without endothelium, from the previously injured site than in those from the non-injured site. Endothelium-dependent relaxation in response to serotonin was comparable at the injured and non-injured sites.
  
  
  CONCLUSIONS
  These results suggest that the coronary hyperconstriction response to serotonin 1 week after injury results primarily from hyperreactivity of vascular smooth muscle. Whereas any contribution of endothelial dysfunction or the geometric effect may be minimal.
authors.affiliation: Research Institute of Angiocardiology and Cardiovascular Clinic, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kuga
authors.forename: T
authors.initials: T
authors.lastname: Kadokami
authors.forename: K
authors.initials: K
authors.lastname: Kuwata
authors.forename: H
authors.initials: H
authors.lastname: Hata
authors.forename: Y
authors.initials: Y
authors.lastname: Ohara
authors.forename: K
authors.initials: K
authors.lastname: Egashira
authors.forename: H
authors.initials: H
authors.lastname: Shimokawa
authors.forename: A
authors.initials: A
authors.lastname: Takeshita
mesh_terms: D000818:Animals; D002404:Catheterization / Q000009:adverse effects; D017023:Coronary Angiography; D003331:Coronary Vessels / Q000166:cytology / Q000293:injuries / Q000503:physiopathology*; D004195:Disease Models, Animal; D008297:Male; D008855:Microscopy, Electron, Scanning; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000503:physiopathology* / Q000648:ultrastructure; D012701:Serotonin / Q000494:pharmacology; D013552:Swine; D013556:Swine, Miniature; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*
chemical_list: D012701:Serotonin