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Peroxide induces vasoconstriction in the human placenta by stimulating thromboxane
1Department of Obstetrics and Gynecology, Medical College of Virginia, Virginia, Commonwealth University, Richmond 23298-0034.
American Journal of Obstetrics and Gynecology
|October 1, 1993
Summary
Lipid peroxides in preeclampsia cause placental vasoconstriction by increasing thromboxane production. Aspirin and thromboxane blockers prevent this effect, indicating thromboxane synthesis is the key mechanism.
Area of Science:
- Obstetrics and Gynecology
- Cardiovascular Physiology
- Biochemistry
Background:
- Preeclampsia is associated with elevated placental lipid peroxides and thromboxane.
- Thromboxane is a potent vasoconstrictor impacting placental vasculature.
- Peroxides may stimulate cyclooxygenase, increasing thromboxane and causing placental vasoconstriction.
Purpose of the Study:
- To investigate if peroxides induce vasoconstriction in human placenta via enhanced thromboxane production.
- To test the hypothesis linking peroxide-induced vasoconstriction to thromboxane synthesis.
Main Methods:
- Isolated human placental cotyledons were perfused with t-butyl hydroperoxide.
- Perfusion was conducted with and without low-dose aspirin or a thromboxane receptor blocker (SQ 29,548).
- Vascular resistance, thromboxane B2, and 6-keto-prostaglandin F1 alpha levels were measured.
Main Results:
- Peroxide perfusion significantly increased vascular resistance and thromboxane B2 secretion.
- The thromboxane B2/6-keto-prostaglandin F1 alpha ratio increased threefold on the fetal side.
- Aspirin blocked peroxide-induced vasoconstriction and thromboxane increase; the thromboxane receptor blocker prevented vasoconstriction but not thromboxane increase.
Conclusions:
- Peroxides induce placental vasoconstriction by stimulating thromboxane synthesis.
- Low-dose aspirin inhibits both thromboxane secretion and vasoconstriction.
- Thromboxane receptor antagonists prevent vasoconstriction, confirming thromboxane's role in peroxide-induced placental vascular changes.
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