title: Hemodynamic effects of platelet-activating factor in nonpregnant and pregnant sheep.
abstract: The present study was designed to assess the dose-related effects of platelet-activating factor (PAF) on systemic, renal, and uterine hemodynamics in nonpregnant sheep and to evaluate how pregnancy might alter these responses. Nonpregnant and pregnant (110 +/- 5 days gestation) ewes were instrumented for conscious measurements of maternal mean arterial pressure (MAP), renal blood flow (RBF), uterine blood flow (UBF), hematocrit, and urinary protein concentration. After recovery, dose-response curves to PAF were generated by systemic infusion at 10, 30, and 100 ng. kg(-1). min(-1) (15 min/dose) into the maternal femoral vein. The above parameters were measured, and renal and uterine vascular resistances (RVR and UVR, respectively) were calculated. In pregnant sheep, PAF increased MAP, RVR, UVR, and urinary protein concentration. We also observed increases in hematocrit, indicative of reduced blood volume secondary to increased systemic microvascular protein permeability. These responses were similar in nonpregnant sheep, with the exception of UVR in nonpregnant ewes being decreased (and thus UBF was increased), whereas in pregnant sheep, UVR was increased, which resulted in decreased UBF. This suggests that pregnancy alters the mechanism of action of PAF within the uterine vasculature in a way that can reduce UBF and thereby potentially compromise placental perfusion.
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, College of Medicine, University of Cincinnati, Cincinnati, Ohio 45267, USA.
authors.forename: S G
authors.initials: SG
authors.lastname: Greenberg
authors.forename: K E
authors.initials: KE
authors.lastname: Clark
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002199:Capillary Permeability / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology*; D010972:Platelet Activating Factor / Q000494:pharmacology / Q000502:physiology*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000187:drug effects / Q000502:physiology*; D011507:Proteinuria / Q000652:urine; D012016:Reference Values; D012039:Regional Blood Flow / Q000187:drug effects; D012079:Renal Circulation / Q000187:drug effects; D014599:Uterus / Q000098:blood supply; D014655:Vascular Resistance / Q000187:drug effects
chemical_list: D010972:Platelet Activating Factor