title: Endothelial-dependent dynamic and antithrombotic properties of porcine aortic and pulmonary valves.
abstract: BACKGROUND
  In the present study, the endothelium-dependent antithrombotic and dynamic properties of porcine aortic (AoV) and pulmonary valves (PuV) were investigated.
  
  
  METHODS
  Fifteen fresh AoV and 15 fresh PuV were obtained from 25 9-month-old swines. The valves were examined for endothelial function by pharmacologic evaluation (with and without endothelium) of both the endothelial-releasing capacity of prostacyclin and the endothelial-dependent dynamic response to relaxing (acetylcholine from 10[-10] mol/L to 10[-4] mol/L in AoV and PuV segments precontracted with norepinephrine [3 x 10(-6) mol/L]) and contracting (endothelin-1, from 10[-11] mol/L to 10[-5] mol/L; and NG-monomethyl-L-arginine, 10[-4] mol/L) drugs. The ultrastructural integrity of the endothelial valve layer was also examined with transmission electron microscopy.
  
  
  RESULTS
  Acetylcholine caused potent relaxation in both AoV and PuV specimens with, but not in those without, endothelium. Endothelin-1 produced a concentration-dependent tension increase in AoV and PuV with and without endothelium. However, the intrinsic activity of the peptide significantly increased in tissues without endothelium. NG-monomethyl-L-arginine evoked a progressive increase in resting tension of the preparations, but the AoV and PuV without endothelium were less sensitive to the inhibition of the nitric oxide generation. Aortic and pulmonary valves with an intact endothelium showed a spontaneous ability to release prostacyclin. The basal release of this lipidic autacoid significantly decreased in cardiac valves without endothelium. This phenomenon was observed in both basal conditions, and under stimulation with the aforementioned drugs. Transmission electron microscopy showed the perfect preservation of endothelial cells in all the preparations examined.
  
  
  CONCLUSIONS
  Valvular endothelium of AoV and PuV seems to have similar antithrombotic and dynamic functions of vascular endothelium, actively participating in valvular homeostasis.
authors.affiliation: Department of Cardiac Surgery, University of Milan, Centro Cardiologico I Monzino Foundation IRCCS, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Pompilio
authors.forename: G
authors.initials: G
authors.lastname: Rossoni
authors.forename: A
authors.initials: A
authors.lastname: Sala
authors.forename: G L
authors.initials: GL
authors.lastname: Polvani
authors.forename: F
authors.initials: F
authors.lastname: Berti
authors.forename: L
authors.initials: L
authors.lastname: Dainese
authors.forename: M
authors.initials: M
authors.lastname: Porqueddu
authors.forename: P
authors.initials: P
authors.lastname: Biglioli
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001021:Aortic Valve / Q000502:physiology*; D012898:Autacoids / Q000378:metabolism; D019332:Endothelin-1 / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D004791:Enzyme Inhibitors / Q000494:pharmacology; D011464:Epoprostenol / Q000378:metabolism; D005343:Fibrinolytic Agents / Q000494:pharmacology*; D006706:Homeostasis; D008854:Microscopy, Electron; D009569:Nitric Oxide / Q000037:antagonists & inhibitors; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D009638:Norepinephrine / Q000494:pharmacology; D010975:Platelet Aggregation Inhibitors / Q000378:metabolism; D011664:Pulmonary Valve / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D012898:Autacoids; D019332:Endothelin-1; D004791:Enzyme Inhibitors; D005343:Fibrinolytic Agents; D010975:Platelet Aggregation Inhibitors; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D011464:Epoprostenol; D019001:Nitric Oxide Synthase; D000109:Acetylcholine; D009638:Norepinephrine