The effects of placental extracts from normotensive and preeclamptic women on vasoconstriction and oxidative metabolism.
OBJECTIVE
A circulating factor derived from the placenta has been implicated in the pathogenesis of preeclampsia. The aim of this study was to determine whether placental extracts from normotensive women and women with preeclampsia increase oxidative metabolism and histamine-induced vasoconstriction in porcine carotid artery.


METHODS
Placental extracts from normotensive women and women with preeclampsia were applied to porcine carotid artery, and oxidative metabolism was measured. Histamine-induced isometric force responses were also determined in the absence and presence of placental extracts.


RESULTS
Application of placental extracts to porcine carotid artery caused a fall in oxygen tension, which reflects increased consumption. Extracts from placentas taken from women with preeclampsia caused a greater fall than those from normotensive women (0.117 +/- 0.026 vs 0.018 +/- 0.0024 micromol oxygen per milligram; P < or =.01). Histamine-induced contractions were potentiated by extracts from preeclampsia but not from those of women without hypertension. The maximal steady-state force values were 13,137 +/- 3647, 12,921 +/- 3684, and 21,673 +/- 7189 N/m(-2) for control, normotensive, and preeclamptic samples at 10-micromol/L histamine (P < or =.05, compared with control placental extracts).


CONCLUSIONS
Placental extracts from women with preeclampsia cause a greater stimulation of porcine artery oxygen consumption and exacerbation of histamine-induced vasoconstriction than extracts from normotensive women.
Department of Biochemistry, University of Oxford, UK.
N F
NF
Thomson
S
S
Thornton
J F
JF
Clark
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002339:Carotid Arteries / Q000187:drug effects; D005260:Female; D006632:Histamine / Q000494:pharmacology; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000494:pharmacology; D066298:In Vitro Techniques; D007537:Isometric Contraction; D008274:Magnesium / Q000378:metabolism; D008297:Male; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D010920:Placenta / Q000503:physiopathology*; D011225:Pre-Eclampsia / Q000503:physiopathology*; D011247:Pregnancy; D013552:Swine; D014020:Tissue Extracts / Q000494:pharmacology*; D014661:Vasoconstriction / Q000187:drug effects*
D006893:Hydroxyeicosatetraenoic Acids; D014020:Tissue Extracts; C025984:15-hydroxy-5,8,11,13-eicosatetraenoic acid; D006632:Histamine; D008274:Magnesium; D002118:Calcium