Placental transfer and maternal and fetal hemodynamic effects of ketanserin in the pregnant ewe.
OBJECTIVE
To determine placental transfer of ketanserin and to assess the effect of serotonin-2 receptor blockade by ketanserin on serotonin- and phenylephrine-induced vasoconstriction.


METHODS
Five chronically instrumented pregnant ewes at 120 days gestation were injected with 20 mg ketanserin i.v., and fetal and maternal arterial samples were obtained at predetermined intervals to assess placental transfer. Maternal and fetal responses of blood flows and pressures were determined after injected of serotonin (20 micrograms/kg) or phenylephrine (10 micrograms/kg) before and after ketanserin (0.75 mg/kg).


RESULTS
In the ewe, ketanserin is transferred across the placenta and reaches measurable levels in the fetal lamb. Ketanserin blocks the maternal and fetal serotonin-induced rise in arterial pressure, but not the serotonin-induced reduction in uterine blood flow.


CONCLUSIONS
In the pregnant ewe, the serotonin-induced rise in maternal and fetal blood pressure is effectively antagonized by ketanserin, whereas the serotonin-induced reduction in uterine blood flow is not.
Schneider
T J
TJ
Department of Obstetrics and Gynecology, School of Medicine and Health Sciences, Erasmus University, Rotterdam, The Netherlands. schneider@gyno.fgg.eru.nl
Struijk
P C
PC
Lotgering
F K
FK
Wallenburg
H C
HC
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D005260:Female; D005333:Fetus / Q000098:blood supply*; D006207:Half-Life; D006439:Hemodynamics / Q000187:drug effects*; D006863:Hydrogen-Ion Concentration; D007650:Ketanserin / Q000493:pharmacokinetics / Q000494:pharmacology*; D008431:Maternal-Fetal Exchange; D010656:Phenylephrine / Q000494:pharmacology; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D011942:Receptors, Adrenergic, alpha / Q000502:physiology; D011985:Receptors, Serotonin / Q000502:physiology; D012702:Serotonin Antagonists / Q000494:pharmacology*; D012756:Sheep
D000317:Adrenergic alpha-Antagonists; D011942:Receptors, Adrenergic, alpha; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D010656:Phenylephrine; D007650:Ketanserin