title: Plasma levels and vascular effects of endothelin and big endothelin in patients with stable and unstable angina pectoris undergoing coronary bypass grafting.
abstract: OBJECTIVE
  The aim of this study was to determine the plasma and pericardial levels of endothelin-1 (ET-1) and its precursor big endothelin-1 (Big ET-1) in patients with unstable and stable angina prior to and following coronary bypass surgery. To further investigate the content of ET-1, tissue levels were studied in the internal mammary artery (IMA) in patients with stable and unstable angina pectoris. Finally, the difference in reactivity of the IMA to ET-1 and Big ET-1 in stable and unstable patients was evaluated.
  
  
  METHODS
  Plasma and pericardial levels of ET-1 and Big ET-1 were determined with radioimmunoassay in 81 patients (33 unstable) immediately before coronary bypass surgery, and at 6, 14, 40 and 64 h following the procedure. Specimens of the distal IMA from 12 patients (six unstable) were collected at the beginning of surgery for determination of tissue levels of ET-1. Additionally, distal internal mammary arteries were obtained from another 24 patients (12 unstable). These vessels were mounted in organ baths for functional studies on vascular reactivity to ET-1 and Big ET-1.
  
  
  RESULTS
  The peripheral plasma levels of ET-1 in unstable patients were significantly lower in patients with unstable angina compared with patients with stable angina pectoris at all points of measurement. The levels of Big ET-1 were significantly higher pre-operatively in the unstable group, but decreased to similar levels to those of stable patients following coronary bypass grafting. There was no difference in ET-1 tissue content in the IMA between the patients. ET-1 and Big ET-1 caused an endothelin(A) (ET(A))-receptor blocker sensitive, concentration-dependent contraction of the IMA obtained from stable as well as unstable patients.
  
  
  CONCLUSIONS
  It is concluded that unstable angina pectoris is associated with an increased ET-1 turnover. This increased turnover may participate in the local regulation of coronary vascular tone with subsequent influence of the condition of the patients. The present investigation also implies that ET(A)-blockade may be useful as an additional pharmacological principal in the treatment of unstable angina pectoris prior to revascularization, as well as to prevent post-operative arterial graft spasm.
authors.affiliation: Department of Thoracic Surgery, Karolinska Hospital, 171 76, Stockholm, Sweden
authors.forename: Ulf
authors.initials: U
authors.lastname: Lockowandt
authors.forename: Staffan
authors.initials: S
authors.lastname: Bjessmo
authors.forename: Torbjörn
authors.initials: T
authors.lastname: Ivert
authors.forename: Anders
authors.initials: A
authors.lastname: Franco-Cereceda
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000787:Angina Pectoris / Q000097:blood / Q000601:surgery*; D000789:Angina, Unstable / Q000097:blood / Q000601:surgery; D015415:Biomarkers / Q000032:analysis; D001026:Coronary Artery Bypass / Q000379:methods*; D019332:Endothelin-1 / Q000032:analysis*; D016232:Endothelins / Q000032:analysis*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008323:Mammary Arteries / Q000737:chemistry; D008875:Middle Aged; D009206:Myocardium / Q000737:chemistry; D011184:Postoperative Period; D011300:Preoperative Care; D011336:Probability; D011446:Prospective Studies; D011498:Protein Precursors / Q000032:analysis*; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D019332:Endothelin-1; D016232:Endothelins; D011498:Protein Precursors