title: Fetal and postnatal ovine mesenteric vascular reactivity.
abstract: BACKGROUND
  Intestinal circulation and mesenteric arterial (MA) reactivity may play a role in preparing the fetus for enteral nutrition. We hypothesized that MA vasoreactivity changes with gestation and vasodilator pathways predominate in the postnatal period.
  
  
  METHODS
  Small distal MA rings (0.5-mm diameter) were isolated from fetal (116-d, 128-d, 134-d, and 141-d gestation, term ~ 147 d) and postnatal lambs. Vasoreactivity was evaluated using vasoconstrictors (norepinephrine (NE) after pretreatment with propranolol and endothelin-1(ET-1)) and vasodilators (NO donors A23187 and s-nitrosopenicillamine (SNAP)). Protein and mRNA assays for receptors and enzymes (endothelin receptor A, alpha-adrenergic receptor 1A (ADRA1A), endothelial NO synthase (eNOS), soluble guanylyl cyclase (sGC), and phosphodiesterase5 (PDE5)) were performed in mesenteric arteries.
  
  
  RESULTS
  MA constriction to NE and ET-1 peaked at 134 d. Relaxation to A23187 and SNAP was maximal after birth. Basal eNOS activity was low at 134 d. ADRA1A mRNA and protein increased significantly at 134 d and decreased postnatally. sGC and PDE5 protein increased from 134 to 141 d.
  
  
  CONCLUSIONS
  Mesenteric vasoconstriction predominates in late-preterm gestation (134 d; the postconceptional age with the highest incidence of necrotizing enterocolitis (NEC)) followed by a conversion to vasodilatory influences near the time of full-term birth. Perturbations in this ontogenic mechanism, including preterm birth, may be a risk factor for NEC.
authors.affiliation: Department of Pediatrics, University at Buffalo, Buffalo, New York.
authors.forename: Jayasree
authors.initials: J
authors.lastname: Nair
authors.affiliation: Department of Pediatrics, University at Buffalo, Buffalo, New York.
authors.forename: Sylvia F
authors.initials: SF
authors.lastname: Gugino
authors.affiliation: Department of Pediatrics, University at Buffalo, Buffalo, New York.
authors.forename: Lori C
authors.initials: LC
authors.lastname: Nielsen
authors.affiliation: Department of Surgery, Yale New Haven Children's Hospital, New Haven, Connecticut.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Caty
authors.affiliation: Department of Pediatrics, University at Buffalo, Buffalo, New York.
authors.forename: Satyan
authors.initials: S
authors.lastname: Lakshminrusimha
mesh_terms: D000818:Animals; D066298:In Vitro Techniques; D008638:Mesenteric Arteries / Q000196:embryology* / Q000502:physiology; D011506:Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012756:Sheep / Q000196:embryology*
chemical_list: D011506:Proteins; D012333:RNA, Messenger