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ß-Carotene Attenuates Peroxide-Induced Vasoconstriction in the Human Placenta

Angele D. Romney, BS

Yuping Wang, MD, PhD

Scott W. Walsh, Phd

Departments of Obsterrics and Gynecology and Physiology, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia

Objective: Placental lipid peroxides and thromboxane are abnormally increased in preeclampsia. Peroxides stimulate thromboxane to increase placental vasoconstriction. antioxidants, such as ß-carotene, control lipid peroxidation. Reduced levels of ßcarotene (0.25 µmol/L) have been found in preeclamptic women. We hypothesized that normal (0.5 µmol/L) or elevated (1.0 µmol/L) levels of ß-carotene would attenuate peroxide-induced vasoconstriction in the human placenta, whereas low levels would not.

Methods: Isolated human placental cotyledons (n = 8) were sequentially perfused with control Krebs-Ringer-bicarbonate buffer, 200 µmol/L t-butyl hydroperoxide, and then with progressively increasing concentrations of ß-carotene (0.25, 0.5, and 1 µmol/L) plus t-butyl hydroperoxide. Fetal perfusion pressure was monitored continuously, and maternal and fetal effluent samples were collected for each treatment. Samples were analyzed for lipid peroxides and for thromboxane and prostacyclin by their stable metabolites thromboxane B₂ (TXB₂) and 6-keto-prostaglandin (PG)F₁.

Results: Compared with control, t-butyl hydroperoxide significantly increased perfusion pressur, vascular resistance, and the secretion rates of lipid peroxides, TXB₂ and 6-keto-PGF₁. Perfusion with normal (0.5 µmol/L) or increased (1 µmol/L) levels of ß-carotene significantly or completely inhibited t-butyl hydroperoxide-induced vasoconstriction and the increases in lipid peroxide and TXB₂ secretion, but did not inhibit peroxide-induced increases in 6-keto-PGF₁ secretion. reduced levels of ß-carotene (0.25 µmol/L) did not inhibit t-butyl hydroperoxide-induced vasoconstriction or the increases in lipid peroxide secretion.

Concluisons: ß-carotene at levels found in normal pregnant women (0.5 µmol/L) or at levels achieved with ß-carotene supplementation (1 µmol/L) inhibited peroxide-induced vasoconstriction and lipid peroxide and thromboxane secretion. Levels of ß-carotene found in preeclamptic women (0.25 µmol/L) did not inhibit peroxide-induced vasoconstriction or lipid peroxide secretion.

Key Words: Lipid peroxides • ß-carotene • placenta • preeclampsia • thromboxane • prostacyclin

Journal of the Society for Gynecologic Investigation, Vol. 4, No. 2, 64-71 (1997)
DOI: 10.1177/107155769700400203


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