Biomaterial Database

Evidence for functional thromboxane A2-prostaglandin H2 receptors in human placenta. 1989

A Hedberg, and P F Mento, and E C Liu, and A M Hollander, and B M Wilkes

Department of Pharmacology, Squibb Institute for Medical Research, Princeton, New Jersey 08543-4000.

The aim of this investigation was to study the role of thromboxane (TX) A2 in the modulation of human fetoplacental vascular resistance. By use of the isolated perfused fetoplacental cotyledon, TX generation (measured by direct radioimmunoassay of TXB2) was demonstrated on the fetal side of the placental circulation. The stable TX mimetic U-46619 caused a dose-dependent increase in perfusion pressure that was inhibited by the TX receptor antagonist SQ 29548. To further characterize the putative TXA2-prostaglandin H2 receptors, binding studies were performed in placental membranes using [3H]SQ 29548. Kinetic analysis revealed rapid and reversible specific binding of [3H]SQ 29548. Saturation binding and Scatchard analysis indicated radioligand binding to a single class of receptors (dissociation constant, 9.11 +/- 0.60 nM; receptor density, 103 +/- 8 fmol/mg protein, n = 4). Prostaglandins D2, E1, E2, F2a, and I2 did not inhibit the specific binding of [3H]SQ 29548 at concentrations less than or equal to 10 microM. This study demonstrates that the human placenta produces and releases TXA2, which can act locally via specific receptor sites to constrict the fetoplacental vasculature.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D010920	Placenta	A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (CHORIONIC VILLI) derived from TROPHOBLASTS and a maternal portion (DECIDUA) derived from the uterine ENDOMETRIUM. The placenta produces an array of steroid, protein and peptide hormones (PLACENTAL HORMONES).	Placentoma, Normal,Placentome,Placentas,Placentomes
D011247	Pregnancy	The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.	Gestation,Pregnancies
D011449	Prostaglandin Endoperoxides	Precursors in the biosynthesis of prostaglandins and thromboxanes from arachidonic acid. They are physiologically active compounds, having effect on vascular and airway smooth muscles, platelet aggregation, etc.	Endoperoxides, Prostaglandin
D011463	Prostaglandins H	A group of physiologically active prostaglandin endoperoxides. They are precursors in the biosynthesis of prostaglandins and thromboxanes. The most frequently encountered member of this group is the prostaglandin H2.
D011982	Receptors, Prostaglandin	Cell surface receptors that bind prostaglandins with high affinity and trigger intracellular changes which influence the behavior of cells. Prostaglandin receptor subtypes have been tentatively named according to their relative affinities for the endogenous prostaglandins. They include those which prefer prostaglandin D2 (DP receptors), prostaglandin E2 (EP1, EP2, and EP3 receptors), prostaglandin F2-alpha (FP receptors), and prostacyclin (IP receptors).	Prostaglandin Receptors,Prostaglandin Receptor,Receptor, Prostaglandin,Receptors, Prostaglandins,Prostaglandins Receptors
D002462	Cell Membrane	The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.	Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D005231	Fatty Acids, Unsaturated	FATTY ACIDS in which the carbon chain contains one or more double or triple carbon-carbon bonds.	Fatty Acids, Polyunsaturated,Polyunsaturated Fatty Acid,Unsaturated Fatty Acid,Polyunsaturated Fatty Acids,Acid, Polyunsaturated Fatty,Acid, Unsaturated Fatty,Acids, Polyunsaturated Fatty,Acids, Unsaturated Fatty,Fatty Acid, Polyunsaturated,Fatty Acid, Unsaturated,Unsaturated Fatty Acids
D005260	Female		Females
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man