The action of nitric oxide in the perfused human fetal-placental circulation.
Nitric oxide is thought to be the endogenous endothelium-derived relaxing factor. We investigated the effects of compounds that either generate nitric oxide intracellularly or inhibit its action on the vasculature of the human placental villus. Addition to perfusion medium of methylene blue (10(5) mol/L), which is an inhibitor of activation of guanylate cyclase by nitric oxide, significantly increased perfusion pressure of the fetal-placental circulation over a range of flow rates (1 to 10 ml/min) compared with the perfusion pressures seen in the absence of methylene blue. This suggests basal release of nitric oxide may contribute to maintenance of resting vascular tone. Both glyceryl trinitrate (10(-9) to 5 x 10(6) mol/L) and S-nitroso-N-acetylpenicillamine (10(-8) to 10(-4) mol/L), which generate nitric oxide intracellularly, were able to significantly vasodilate the fetal-placental circulation preconstricted with the thromboxane mimetic U46619 (1 to 5 x 10(-8) mol/L) in a concentration-dependent manner. These compounds had no effect in the absence of the vasoconstrictor. Thus it appears that the placental villus tree has the ability to both generate and respond to nitric oxide.
Myatt
L
L
Department of Obstetrics and Gynecology, University of Cincinnati, OH 45267.
Brewer
A
A
Brockman
D E
DE
D001783:Blood Flow Velocity / Q000187:drug effects; D002824:Chorionic Villi / Q000098:blood supply / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005333:Fetus / Q000098:blood supply* / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D008751:Methylene Blue / Q000494:pharmacology; D009569:Nitric Oxide / Q000494:pharmacology*; D005996:Nitroglycerin / Q000494:pharmacology; D010396:Penicillamine / Q000031:analogs & derivatives / Q000494:pharmacology; D010477:Perfusion / Q000379:methods; D010920:Placenta / Q000098:blood supply* / Q000187:drug effects; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D012039:Regional Blood Flow / Q000187:drug effects; D026423:S-Nitroso-N-Acetylpenicillamine; D014655:Vascular Resistance / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology
D011450:Prostaglandin Endoperoxides, Synthetic; D014665:Vasodilator Agents; D009569:Nitric Oxide; D026423:S-Nitroso-N-Acetylpenicillamine; D005996:Nitroglycerin; D010396:Penicillamine; D008751:Methylene Blue