Expression of phosphodiesterase 5 in maternal and fetal sheep

Am J Obstet Gynecol. 2005 Sep;193(3 Pt 2):1005-10. doi: 10.1016/j.ajog.2005.05.054.


Objective: Ovine pregnancy is associated with elevated levels of nitric oxide. Nitric oxide stimulates cyclic guanosine monophosphate (cGMP), which results in vascular smooth muscle relaxation/vasodilation. Phosphodiesterase type 5 regulates cGMP in the urogenital track. The present study was designed to determine message expression of phosphodiesterase type 5 in the myometrium, uterine vessels, and placentome of the sheep and phosphodiesterase type 5 protein expression in the maternal and fetal placentome.

Study design: Tissue was collected from 5 nonpregnant and 5 pregnant anesthetized animals (gestational day = 134 +/- 4) and frozen at -80 degrees C. Optimized reverse transcription-polymerase chain reaction was performed on all tissues, and immunohistochemistry was performed on the placentome only.

Results: Phosphodiesterase type 5 messenger ribonucleic acid levels were significantly higher in the myometrium and placentome, compared with the maternal blood vessels. Phosphodiesterase type 5 protein was immuno-localized to the vascular smooth muscle of the maternal vessels, stroma, and placental capsule only.

Conclusion: Although phosphodiesterase type 5 messenger ribonucleic acid was present in the fetal placenta, phosphodiesterase type 5 protein was expressed only in maternally derived placental tissue. This suggests that regulation of cGMP levels and vascular tone in the umbilical circulation differs from the uterine circulation.

MeSH terms

  • 3',5'-Cyclic-GMP Phosphodiesterases
  • Animals
  • Cyclic GMP / physiology
  • Cyclic Nucleotide Phosphodiesterases, Type 5
  • Female
  • Fetal Blood / physiology*
  • Immunohistochemistry
  • Myometrium / metabolism
  • Phosphoric Diester Hydrolases / metabolism*
  • Placenta / metabolism*
  • Pregnancy
  • RNA, Messenger / metabolism
  • Regional Blood Flow / physiology
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sheep
  • Uterus / blood supply*


  • RNA, Messenger
  • Phosphoric Diester Hydrolases
  • 3',5'-Cyclic-GMP Phosphodiesterases
  • Cyclic Nucleotide Phosphodiesterases, Type 5
  • Cyclic GMP