title: Prostaglandins are responsible for the inhibition of breathing observed with a placental extract in fetal sheep.
abstract: We have previously observed that the infusion of a placental extract inhibits breathing movements in fetal sheep, suggesting that a placental factor may be responsible for the inhibition of fetal breathing. Our preliminary results suggested that a small peptide or a substance bound to a peptide was likely responsible for this inhibition. Since prostaglandins are found in high concentrations in the placenta, it is possible that they may be responsible for the inhibition of breathing observed with the placental extract. We hypothesized that if prostaglandins were the active factors in the placental extract, then inhibition of the production of placental prostaglandins should eliminate the activity of the extract. We infused untreated and indomethacin/ASA-treated placental extracts into the carotid artery of eight chronically instrumented fetal sheep continuously over 3 h. The concentration of all prostaglandins measured in the untreated placental extracts were significantly higher than in the indomethacin/ASA-treated extracts. Only the infusion of the untreated placental extract induced a significant decreased in the incidence of fetal breathing. Fetal plasma prostaglandins increased significantly only with the infusion of the untreated placental extracts. These findings suggest that the inhibition of breathing observed with the placental extract is likely related to prostaglandins.
authors.affiliation: Departments of Pediatrics, Physiology and Reproductive Medicine, University of Manitoba, WR004--Women's Hospital, 735 Notre Dame Avenue, Winnipeg, Man., Canada R3E 0L8. ralvaro@cc.umanitoba.ca
authors.forename: Ruben E
authors.initials: RE
authors.lastname: Alvaro
authors.forename: Shabih U
authors.initials: SU
authors.lastname: Hasan
authors.forename: Sylvain
authors.initials: S
authors.lastname: Chemtob
authors.forename: Mansour
authors.initials: M
authors.lastname: Qurashi
authors.forename: Saif
authors.initials: S
authors.lastname: Al-Saif
authors.forename: Henrique
authors.initials: H
authors.lastname: Rigatto
mesh_terms: D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D005324:Fetal Movement / Q000502:physiology*; D005333:Fetus / Q000502:physiology; D007213:Indomethacin / Q000494:pharmacology; D010920:Placenta / Q000737:chemistry / Q000187:drug effects; D011247:Pregnancy; D011453:Prostaglandins / Q000032:analysis / Q000097:blood / Q000502:physiology*; D012119:Respiration; D015656:Respiratory Mechanics / Q000502:physiology*; D012756:Sheep
chemical_list: D004791:Enzyme Inhibitors; D011453:Prostaglandins; D007213:Indomethacin