title: Physiologic significance of 17beta-estradiol binding in the rabbit Fallopian tube.
abstract: Rabbit Fallopian tube contractility was recorded in vitro during perfusion with either Locke's solution or that solution containing CN-55, 945-27 (CN; or CI-628), a nonsteroidal estrogen antagonist (Endocrinology 79: 153, 1966). Contractility was inhibited and 17beta-estradiol (E2) displaced from both its cytoplasmic (8S) and nuclear (4S) receptors in the presence of the above agent. These effects result from a direct interaction between CN and the E2-receptor complexes. Two types of evidence show the specificity of the foregoing responses: (1) nonspecific binding of E2 to serum proteins was unaffected by the antagonist and (2) CN had no effect on contractility of a nontarget tissue, i.e., rabbit ileum. In addition, Fallopian tube contractions induced by strong electrical stimulation of K-depolarized tissues (i.e., in the absence of normal ionic gradients) were inhibited by CN and a decrease in the binding capacities of 8S and 4S receptors was again observed. Thus, antagonism of specific E2 binding inhibits the contractile mechanism at a level other than the cell membrane. These observations, and additional findings concerning the reversibility of CN action, indicate that E2 binding is essential for contractility of the rabbit Fallopian tube.
mesh_terms: D000818:Animals; D003470:Culture Media; D004558:Electric Stimulation; D004958:Estradiol / Q000378:metabolism*; D005187:Fallopian Tubes / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D005260:Female; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009594:Nitromifene / Q000494:pharmacology; D011485:Protein Binding; D011817:Rabbits; D011956:Receptors, Cell Surface; D014316:Tritium
chemical_list: D003470:Culture Media; D011956:Receptors, Cell Surface; D014316:Tritium; D004958:Estradiol; D009594:Nitromifene