title: 'Specific receptor binding' of radioactively labeled products of radiolysis of the estrogen receptor ligand R 2858 (17 alpha-ethynyl-11 beta-methoxy-estradiol-17 beta).
abstract: Radioactively labeled steroids undergo decomposition processes, which are dependent on time, storage conditions (temperature, solvents etc.), degree of labeling etc. This communication shows that several decomposition products of 17 alpha-ethynyl-11 beta-methoxy-estradiol-17 beta (R 2858) bind to rat uterine cytosol in a way that would be interpreted as 'specific receptor binding' if some of these compounds were present in the ligand solution used for estrogen receptor determination. Thus, the binding was charcoal-resistant and displaceable with an excess of unlabeled R 2858, and the percentage of binding was of significant magnitude to seriously interfere with receptor measurements.
mesh_terms: D000818:Animals; D003600:Cytosol / Q000378:metabolism; D004355:Drug Stability; D045166:Estradiol Congeners / Q000378:metabolism*; D004997:Ethinyl Estradiol / Q000031:analogs & derivatives* / Q000378:metabolism; D005260:Female; D051381:Rats; D011960:Receptors, Estrogen / Q000378:metabolism*; D014316:Tritium; D014599:Uterus / Q000378:metabolism
chemical_list: D045166:Estradiol Congeners; D011960:Receptors, Estrogen; D014316:Tritium; D004997:Ethinyl Estradiol; C011310:moxestrol