Receptor binding in various tissues of PGE2, PGF2α and sulprostone, a novel PGE2-derivative

Sulprostone is a tissue-specific PGE₂-derivative with high abortifacient activity in various species including man. The dissociation constant K_D of the receptor binding of this compound was compared with PGE₂ and PGF_2α in various tissue preparations of different species. A structure-binding relationship was developed from competition curves after a logit/log transformation. It is demonstrated that the relative affinities of Sulprostone, PGE₂ and PGF_2α remain essentially constant in all the tissues investigated. It is concluded that the tissue-specificity of Sulprostone cannot be ascribed to structural differences of the receptor molecule.