title: Differential effect of insulin like growth factor-I on constriction of human uterine and placental arteries.
abstract: BACKGROUND
  Discrete regulation of the uterine and placental vasculatures is an important feature of uteroplacental perfusion and pregnancy success because appropriate maternal/fetal exchange of nutrients and gases is crucial for normal fetal growth. Placental vasculature lacks autonomic innervation so tone is controlled by locally derived vasoactive factors. IGF-I, which is produced by the placenta, is critical for normal fetal growth and studies of animal vascular systems have shown that IGF-I regulates vasomotor tone.
  
  
  OBJECTIVE
  The objective of the study was to determine whether IGF-I directly alters human placental and myometrial arterial tone in vitro.
  
  
  METHODS
  Women with uncomplicated pregnancy delivering a singleton infant at term participated in the study.
  
  
  METHODS
  The study was conducted at university hospital laboratories.
  
  
  METHODS
  Comparison of arterial tension measured before and after exposure to IGF-I.
  
  
  METHODS
  Placental and myometrial arteries were mounted on a wire myograph, exposed to the constrictor U46619 (10(-10) to 10(-5) m), returned to baseline tension, and then incubated with IGF-I (0-500 ng/ml) for various time points before performing a second dose-response curve to U46619. IGF-I receptor protein expression was assessed.
  
  
  RESULTS
  IGF-I did not acutely alter the response of placental arteries to U46619. Exposure of myometrial arteries to IGF-I caused a rightward shift of U46619 dose-response curves (P < 0.05); EC(50) data were significantly increased at 30 (15.5 ± 2.8 vs. 133 ± 44 nm, before and after IGF treatment, respectively) and 60 min (10.9 ± 1.9 vs. 146 ± 47 nm). Placental and myometrial arteries had a similar IGF-I receptor expression profile.
  
  
  CONCLUSIONS
  IGF-I acutely modulates the vasomotor tone of human myometrial, but not placental, arteries, suggesting that IGF-I regulates the delivery of maternal blood to the placenta.
authors.affiliation: Maternal and Fetal Health Research Centre, University of Manchester, St. Mary's Hospital, Oxford Road, Manchester M13 9WL, United Kingdom.
authors.forename: Jemma J
authors.initials: JJ
authors.lastname: Corcoran
authors.forename: Jayne C
authors.initials: JC
authors.lastname: Charnock
authors.forename: Julie
authors.initials: J
authors.lastname: Martin
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Taggart
authors.forename: Melissa
authors.initials: M
authors.lastname: Westwood
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000328:Adult; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D010920:Placenta / Q000098:blood supply* / Q000187:drug effects / Q000378:metabolism; D011247:Pregnancy; D017526:Receptor, IGF Type 1 / Q000378:metabolism; D055988:Uterine Artery / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects* / Q000502:physiology; D014662:Vasoconstrictor Agents / Q000494:pharmacology
chemical_list: D014662:Vasoconstrictor Agents; D007334:Insulin-Like Growth Factor I; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D017526:Receptor, IGF Type 1