title: I-labeled 19-iodinated and 6 beta-iodomethyl-19-nor steroids: effect of structural modification on the adrenal accumulation.
abstract: 19-Iodinated and 6 beta-iodomethyl-19-nor derivatives of cholesterol and 17-ketosteroid labeled with 131I were tested in rats to determine the critical structural features required for maximal adrenal uptake. The introduction of the 17-keto group in place of the 17 beta-side chain of cholesterol caused most of the radioactivity to be taken up by the thyroids. Fluorination at the C-3 position had deleterious effects on the adrenal concentration and led to the loss of adrenal specificity. A beta-hydroxy group at the C-3 position is substantially required for adrenal uptake.
mesh_terms: D000311:Adrenal Glands / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D002784:Cholesterol / Q000031:analogs & derivatives*; D007202:Indicators and Reagents; D007457:Iodine Radioisotopes; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013256:Steroids / Q000138:chemical synthesis* / Q000378:metabolism; D013329:Structure-Activity Relationship; D014018:Tissue Distribution
chemical_list: D007202:Indicators and Reagents; D007457:Iodine Radioisotopes; D013256:Steroids; D002784:Cholesterol