title: Characterization of endothelium-dependent relaxations in the mesenteric vasculature: a comparative study with potential pathophysiological relevance.
abstract: BACKGROUND
  Endothelium-dependent relaxations in human adult mesenteric microvessels involve 3 different main mechanisms: cyclooxygenase (COX)-derived prostanoids, nitric oxide (NO), and endothelium-derived hyperpolarizing factor (EDHF), which elicits vascular smooth muscle hyperpolarization and relaxation. There are some pathological conditions with an abnormal balance between mesenteric vasoconstriction and vasodilatation inputs leading to endothelial dysfunction and tissue injury.
  
  
  OBJECTIVE
  The purpose was to characterize the mechanisms mediating endothelium-dependent relaxation and differences in children and adult mesenteric microvessels.
  
  
  METHODS
  Microvessels were dissected from omentum obtained from children (3-6 years old) and adults (25-41 years old) and mounted as ring preparations in a small vessel myograph.
  
  
  RESULTS
  In microvessels precontracted with a thromboxane analogue, the endothelium-dependent relaxations to bradykinin (10 nmol/L to 30 μmol/L) mediated by EDHF, that is, nonsensitive to COX (10 μmol/L indomethacin) and NO synthase blockade (100 μmol/L N-nitro-L-arginine methyl ester), were higher in children than in adults. When EDHF was blunted by a depolarizing precontraction with KCl, the remaining COX- and NO-dependent relaxations were significantly lower in children.
  
  
  CONCLUSIONS
  The EDHF's role in the endothelium-dependent relaxations is higher in children's vasculature. This suggests that endothelial dysfunction in mesenteric microvessels in children is likely more dependent on EDHF-related mechanisms rather than on NO- or COX-derived prostanoids.
authors.affiliation: Division of Pediatric Surgery, San Carlos University Hospital, Madrid 28040, Spain. lrivilla.hcsc@salud.madrid.org
authors.forename: Fernando
authors.initials: F
authors.lastname: Rivilla
authors.forename: Susana
authors.initials: S
authors.lastname: Vallejo
authors.forename: Concepción
authors.initials: C
authors.lastname: Peiró
authors.forename: Carlos F
authors.initials: CF
authors.lastname: Sánchez-Ferrer
mesh_terms: D000328:Adult; D000367:Age Factors; D001685:Biological Factors / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D006801:Humans; D066298:In Vitro Techniques; D055806:Microvessels / Q000378:metabolism / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism; D009852:Omentum / Q000098:blood supply*; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D014664:Vasodilation / Q000502:physiology*
chemical_list: D001685:Biological Factors; D015415:Biomarkers; C067410:endothelium-dependent hyperpolarization factor; D009569:Nitric Oxide; D011451:Prostaglandin-Endoperoxide Synthases