title: Prostanoids contribute to the oxygen-dependent regulation of vascular tone of human umbilical vein.
abstract: OBJECTIVE
  To investigate the contribution of prostanoids to the oxygen-dependent regulation of human umbilical vein vascular tone.
  
  
  METHODS
  Intracellular membrane potential and isometric tension of intact and endothelium-denuded human umbilical vein strips with and without cyclooxygenase inhibition by indomethacin (10(-5) M) were recorded simultaneously during variation of the local pO2.
  
  
  RESULTS
  Decreasing pO2 from 39 to 5 mm Hg resulted in hyperpolarization and decrease in isometric tension of intact preparations. These effects did not occur in indomethacin treated preparations. Endothelium-denuded preparations revealed pronounced depolarization and increase in tension with decreasing pO2. Indomethacin treatment abolished these effects. With increasing pO2 from 39 to 104 mm Hg intact preparations depolarized and isometric tension remained stable. Removal of the endothelium or treatment with indomethacin reversed these effects.
  
  
  CONCLUSIONS
  This study confirms that the human umbilical vein actively regulates its vascular tone which is under the control of PO2. Vasodilating endothelial prostanoids contribute to the hypoxic vasodilatation and thereby counteract the vasoconstricting actions of prostanoids released from vascular smooth muscle cells. Our results indicate that vasoconstricting prostanoids are released from the endothelium of the human umbilical vein at hyperoxia.
authors.affiliation: Department of Pediatrics, Kinderklinik, Universitätsklinikum Benjamin Franklin, Free University Berlin, Germany. eva.mildenberger@medizin.fu-berlin.de
authors.forename: Eva
authors.initials: E
authors.lastname: Mildenberger
authors.forename: Günter
authors.initials: G
authors.lastname: Siegel
authors.forename: Hans T
authors.initials: HT
authors.lastname: Versmold
mesh_terms: D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D007213:Indomethacin / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects* / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D010100:Oxygen / Q000494:pharmacology; D011247:Pregnancy; D011453:Prostaglandins / Q000008:administration & dosage / Q000494:pharmacology*; D012016:Reference Values; D014471:Umbilical Veins / Q000187:drug effects* / Q000502:physiology; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D011453:Prostaglandins; D014665:Vasodilator Agents; D010100:Oxygen; D007213:Indomethacin