title: Vasopressin induces rectosigmoidal mucosal ischemia during cardiopulmonary bypass.
abstract: BACKGROUND
  Lower gastrointestinal complications are rare after cardiac surgery with cardiopulmonary bypass (CPB). However, if they occur, they are associated with a high mortality. Endothelin (ET) expression and microcirculatory dysfunction have been shown to be involved in a variety of diseases of the lower gastrointestinal tract. The aim of this study was to analyze whether CPB with or without additional vasopressin administration affects the rectosigmoidal mucosal microcirculation and whether this involves the ET system.
  
  
  METHODS
  Pigs were randomized in three groups (n = 6 each): I Sham, II CPB: 1 hour CPB, III CPB + vasopressin: 1 hour CPB and vasopressin (0.006 U/min kg) administration maintaining baseline arterial pressure. All animals were reperfused for 90 minutes. During the experiment hemodynamics and rectosigmoidal mucosal microcirculation were measured continuously. The rectosigmoidal mucosal expression of endothelin-1 (ET-1) and its receptor subtypes A (ETA ) and B (ETB ) were determined using PCR and Western blot analysis.
  
  
  RESULTS
  CPB did not change rectosigmoidal microvascular blood flow compared to baseline (68.1 ± 4.0 vs. 75.5 ± 6.6 AU; p = 0.4), but increased ET-1 (gene, 7.8 ± 1.5 vs. 2.3 ± 0.6 RQ; p = 0.002 and protein, 12.0 ± 0.5 vs. 6.9 ± 0.3 OD mm(2) ; p < 0.001), ETA (gene, 2.3 ± 0.6 vs. 0.6 ± 0.1 RQ; p < 0.001 and protein, 11.0 ± 0.3 vs. 6.2 ± 1.1 OD mm(2) ; p = 0.006) and ETB (gene, 6.7 ± 1.2 vs. 1.9 ± 0.3 RQ; p < 0.001 and protein, 25.6 ± 1.4 vs. 14.9 ± 1.5 OD mm(2) ; p = 0.002) expression compared to Sham. Vasopressin during CPB reduced the rectosigmoidal blood flow compared to baseline (26.5 ± 4.9 vs. 75.5 ± 6.6 AU, p < 0.001), and blunted the CPB-induced increase of ET-1 (gene, 1.2 ± 0.4 RQ, p = 0.1 and protein, 8.1 ± 1.6 OD mm(2) , p = 0.5 vs. Sham), ETA (gene, 0.6 ± 0.1 RQ, p = 1.0 and protein, 7.0 ± 0.6 OD mm(2) , p = 0.6 vs. Sham) and ETB (gene, 1.3 ± 0.3 RQ, p = 0.1 and protein, 19.4 ± 2.1 OD mm(2) , p = 0.1 vs. Sham).
  
  
  CONCLUSIONS
  CPB does not significantly affect rectosigmoidal mucosal microcirculation; however, it upregulates ET-1, ETA , and ETB . Vasopressin blunts the CPB-induced elevation of ET-1, ETA , and ETB and induces rectosigmoidal mucosal ischemia during CPB.
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, University Hospital of Saarland, Homburg/Saar, Germany; Department of Anesthesiology, Intensive Care Medicine and Pain Medicine, University Hospital Schleswig-Holstein, Kiel, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Bomberg
authors.forename: B
authors.initials: B
authors.lastname: Bierbach
authors.forename: S
authors.initials: S
authors.lastname: Flache
authors.forename: C
authors.initials: C
authors.lastname: Scheuer
authors.forename: M
authors.initials: M
authors.lastname: Novák
authors.forename: H-J
authors.initials: HJ
authors.lastname: Schäfers
authors.forename: M D
authors.initials: MD
authors.lastname: Menger
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects; D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D012809:Colon, Sigmoid / Q000098:blood supply*; D019332:Endothelin-1 / Q000378:metabolism* / Q000502:physiology; D006439:Hemodynamics / Q000187:drug effects; D007413:Intestinal Mucosa / Q000098:blood supply*; D007511:Ischemia / Q000139:chemically induced*; D008833:Microcirculation / Q000187:drug effects*; D017466:Receptors, Endothelin / Q000378:metabolism; D012007:Rectum / Q000098:blood supply*; D013552:Swine; D015854:Up-Regulation / Q000187:drug effects; D014667:Vasopressins / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D019332:Endothelin-1; D017466:Receptors, Endothelin; D014667:Vasopressins