Clinical trial NCT00005208: Regulation of Placental Vascular Reactivity in Pregnancy-induced Hypertension
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Cardiovascular Diseases
Heart Diseases
Hypertension
Pregnancy Toxemias
Lead sponsor: National Heart, Lung, and Blood Institute (NHLBI)
Sponsor class: NIH
First posted: 2000-05-26
Sex: MALE
Maximum age (years): 100
Standard ages: CHILD
ADULT
OLDER_ADULT
Accepts healthy volunteers: no

Brief summary: To elucidate the role of an imbalance in vasodilator prostacyclin (PGI2) and vasoconstrictor thromboxane (TxA2) in pregnancy-induced hypertension

Detailed description: BACKGROUND:

Pregnancy-induced hypertension (PIH) is associated with increased fetal and neonatal morbidity and mortality possibly resulting from hypoxia in utero. The primary pathology of PIH involves a reduction in uteroplacental blood flow but modern imaging techniques have now shown that increased impedance of the fetal-placental circulation and hence reduced blood flow can also be found in PIH. This may represent a direct effect of hypoxia or be a fetal adaptation to increase placental oxygen extraction to relieve hypoxia. The fetal-placental circulation is regulated by humoral agents and vascular pressure. An imbalance of vasodilator prostacyclin (PGI2) and vasoconstrictor thromboxane (TxA2) production is reported to underlie the vasoconstriction seen in PIH.

The study resulted from the 1986 release of a Request for Applications for Research on Hypertension in Pregnancy by the National Heart, Lung, and Blood Institute and the National Institute of Child Health and Human Development.

DESIGN NARRATIVE:

The fetal-placental circulations of perfused human placental cotyledons from normotensive and pregnancy-induced hypertensive pregnancies were used to determine if an imbalance in PGI2/TxA2 production existed and its relationship to the responses of the fetal-placental circulation to vasoconstriction. Studies were also conducted on the effects of hypocalcemia and hypomagnesemia, hypoxia, and drugs.

The study completion date listed in this record was obtained from the "End Date" entered in the Protocol Registration and Results System (PRS) record.

Eligibility criteria: No eligibility criteria

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References:
citation: Myatt L, Brewer AS, Brockman DE. The comparative effects of big endothelin-1, endothelin-1, and endothelin-3 in the human fetal-placental circulation. Am J Obstet Gynecol. 1992 Dec;167(6):1651-6. doi: 10.1016/0002-9378(92)91756-z.
citation: Myatt L. Control of vascular resistance in the human placenta. Placenta. 1992 Jul-Aug;13(4):329-41. doi: 10.1016/0143-4004(92)90057-z. No abstract available.
citation: Eis AW, Mitchell MD, Myatt L. Endothelin transfer and endothelin effects on water transfer in human fetal membranes. Obstet Gynecol. 1992 Mar;79(3):411-5. doi: 10.1097/00006250-199203000-00017.
citation: Myatt L, Brewer AS, Langdon G, Brockman DE. Attenuation of the vasoconstrictor effects of thromboxane and endothelin by nitric oxide in the human fetal-placental circulation. Am J Obstet Gynecol. 1992 Jan;166(1 Pt 1):224-30. doi: 10.1016/0002-9378(92)91863-6.
citation: Myatt L, Langdon G, Brewer AS, Brockman DE. Endothelin-1-induced vasoconstriction is not mediated by thromboxane release and action in the human fetal-placental circulation. Am J Obstet Gynecol. 1991 Dec;165(6 Pt 1):1717-22. doi: 10.1016/0002-9378(91)90021-i.
citation: Jacobson RL, Brewer A, Eis A, Siddiqi TA, Myatt L. Transfer of aspirin across the perfused human placental cotyledon. Am J Obstet Gynecol. 1991 Oct;165(4 Pt 1):939-44. doi: 10.1016/0002-9378(91)90444-v.
citation: Myatt L, Brewer A, Brockman DE. The action of nitric oxide in the perfused human fetal-placental circulation. Am J Obstet Gynecol. 1991 Feb;164(2):687-92. doi: 10.1016/s0002-9378(11)80047-5.
citation: Myatt L, Brockman DE, Langdon G, Pollock JS. Constitutive calcium-dependent isoform of nitric oxide synthase in the human placental villous vascular tree. Placenta. 1993 Jul-Aug;14(4):373-83. doi: 10.1016/s0143-4004(05)80459-x.