Biomaterial Database

Radioiodide transfer across sheep placenta. 1986

J F Canning, and T E Stacey, and R H Ward, and R D Boyd

Unidirectional transplacental clearances of radioiodide were calculated from the net radioiodide fluxes after injection into fetal and/or maternal circulations of 33 catheterized conscious sheep. Maternofetal potential difference (PD) was also recorded. Clearance reached a steady state 20 min after bolus injection. Fetomaternal clearance was related to PD. Bidirectional clearance ratios measured in five experiments showed a significant divergence from the value for passive flux predicted from the measured PD, and in four experiments these ratios were also significantly different from unity, this result being incompatible with passive flux even if the transplacental PD is assumed to be zero. Injection of thiocyanate or iodide reduced radioiodide clearance. Fetomaternal clearance of radioiodide was halved by an increase in fetal plasma iodide concentration of approximately 0.1 mM. There appears to be an inhibitable iodide-transporting site capable of active transport in either direction.

UI	MeSH Term	Description	Entries
D007267	Injections	Introduction of substances into the body using a needle and syringe.	Injectables,Injectable,Injection
D007454	Iodides	Inorganic binary compounds of iodine or the I- ion.	Iodide
D007455	Iodine	A nonmetallic element of the halogen group that is represented by the atomic symbol I, atomic number 53, and atomic weight of 126.90. It is a nutritionally essential element, especially important in thyroid hormone synthesis. In solution, it has anti-infective properties and is used topically.	Iodine-127,Iodine 127
D008431	Maternal-Fetal Exchange	Exchange of substances between the maternal blood and the fetal blood at the PLACENTA via PLACENTAL CIRCULATION. The placental barrier excludes microbial or viral transmission.	Transplacental Exposure,Exchange, Maternal-Fetal,Exposure, Transplacental,Maternal Fetal Exchange
D008954	Models, Biological	Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.	Biological Model,Biological Models,Model, Biological,Models, Biologic,Biologic Model,Biologic Models,Model, Biologic
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
D011868	Radioisotopes	Isotopes that exhibit radioactivity and undergo radioactive decay. (From Grant & Hackh's Chemical Dictionary, 5th ed & McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Daughter Isotope,Daughter Nuclide,Radioactive Isotope,Radioactive Isotopes,Radiogenic Isotope,Radioisotope,Radionuclide,Radionuclides,Daughter Nuclides,Daugter Isotopes,Radiogenic Isotopes,Isotope, Daughter,Isotope, Radioactive,Isotope, Radiogenic,Isotopes, Daugter,Isotopes, Radioactive,Isotopes, Radiogenic,Nuclide, Daughter,Nuclides, Daughter
D005260	Female		Females
D005333	Fetus	The unborn young of a viviparous mammal, in the postembryonic period, after the major structures have been outlined. In humans, the unborn young from the end of the eighth week after CONCEPTION until BIRTH, as distinguished from the earlier EMBRYO, MAMMALIAN.	Fetal Structures,Fetal Tissue,Fetuses,Mummified Fetus,Retained Fetus,Fetal Structure,Fetal Tissues,Fetus, Mummified,Fetus, Retained,Structure, Fetal,Structures, Fetal,Tissue, Fetal,Tissues, Fetal