title: Heparin neutralization by an extract of the human placenta: measurements and the concept of placental barrier to heparin.
abstract: A soluble extract from human placenta was found to neutralize heparin in a factor Xa-dependent heparin assay system. In comparison with serum the antiheparin activity of placenta tissue is 10 times higher (extract from 1 g of placenta neutralizes 8.94 +/- 3.31 IU of heparin; 1 ml of serum approximately 1 IU). The substance neutralizing heparin has not been identified, but it has been found that it is nondialyzable, is not adsorbed on heparin-Sepharose, and does not act progressively. It was suggested that the substance(s) responsible for the antiheparin effect in vitro might contribute to the failure of heparin to penetrate the placenta in vivo (placental barrier to heparin).
authors.affiliation: Department of Medicine Propedeutics, University School of Medicine, Bydogoszcz, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Uszyński
mesh_terms: D002846:Chromatography, Affinity; D004353:Drug Evaluation, Preclinical; D004347:Drug Interactions; D005260:Female; D006493:Heparin / Q000494:pharmacology*; D006801:Humans; D008431:Maternal-Fetal Exchange; D010924:Placental Extracts / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D011247:Pregnancy
chemical_list: D010924:Placental Extracts; D006493:Heparin