Maternal to fetal thyroxine transmission in the human term placenta is limited by inner ring deiodination
| Autor: | R. S. Addison, Michael S. Roberts, G.R. Cannell, Robin H. Mortimer, John P. Galligan |
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| Rok vydání: | 1996 |
| Předmět: |
medicine.medical_specialty
Mother to child transmission Endocrinology Diabetes and Metabolism Placenta Clinical Biochemistry Deiodinase In Vitro Techniques Iopanoic Acid Biochemistry Iodide Peroxidase Iopanoic acid Term placenta Endocrinology Pregnancy Internal medicine medicine Humans Maternal-Fetal Exchange Fetus biology Term pregnancy Biochemistry (medical) Metabolism Thyroxine medicine.anatomical_structure biology.protein Female medicine.drug Half-Life |
| Zdroj: | The Journal of clinical endocrinology and metabolism. 81(6) |
| ISSN: | 0021-972X |
| Popis: | Placental deiodination of T4 to rT3 has been proposed as the factor controlling materno-fetal transmission of T4. We investigated T4 transfer in the isolated perfused human placental lobule with and without addition of the deiodinase inhibitor, iopanoic acid. T4 (150 nmol/L) in protein-free medium was added to the maternal circuit. Without iopanoic acid, the appearance of T4 in the fetal circuit was very low, with fetal T4 levels reaching only 4.1 +/- 0.84 pmol/L at 6 h. Levels of rT3 rose progressively in both circuits, reaching 28.8 +/- 5.5 nmol/L in the maternal and 12.4 +/- 3.2 nmol/L in the fetal circuit by 6 h. No T3 could be measured in either circuit. Addition of 0.5 nmol/L iopanoic acid to maternal perfusate, however, resulted in significant reduction in the appearance of rT3 [maternal levels, 0.58 +/- 0.06 nmol/L (2% of control values); fetal levels, 0.33 +/- 0.03 nmol/L (2.7% of control values)] and a major (approximately 2700-fold) increase in T4 appearance in the fetal circuit, with fetal T4 levels reaching 10.1 +/- 3.4 nmol/L at 6 h. These results support the hypothesis that placental inner ring (type III) deiodination is a major factor controlling placental transmission of maternal T4. |
| Databáze: | OpenAIRE |
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