Adams A, Jarrott B
Life Sci. 1982 Mar 15;30(11):945-52. doi: 10.1016/0024-3205(82)90623-3.
Two alpha-adrenoceptor antagonists, phentolamine and 2-(beta-(4-hydroxyphenyl)-ethylaminomethyl)-tetralone (BE 2254) which are phenolic derivatives were radioiodinated after chloramine-T oxidation of Na125I and the labelled material isolated by chromatography. 125I-phentolamine does not bind selectively to alpha-adrenoceptors in guinea pig brain whereas the 125I-BE 2254 derivative binds rapidly, reversibly and with high affinity to these receptors with a Kd of 230 pM. At low concentrations of 125I-BE 2254 (less than 100 pM) approx. 90% of the bound radioligand is specifically bound and under these conditions drug displacement studies show that the ligand binds predominantly to the alpha 1 subclass of adrenoceptors. Binding measurements to kidney and smooth muscle membrane preparations indicate that 125I-BE 2254 may also be a useful tool in the study of alpha-adrenoceptors in peripheral tissues. The high specific activity of 125I-BE 2254 permits the use of minimal quantities of membrane material for receptor assay and ligand displacement measurements, e.g. 250 micrograms per assay tube, and this provides a significant advantage over the use of existing radioligands such as 3H-prazosin which requires approx. 40 times as much tissue.
两种α-肾上腺素能受体拮抗剂，酚妥拉明和2-（β-（4-羟基苯基）-乙氨基甲基）-四氢萘酮（BE 2254），它们都是酚类衍生物，在对Na125I进行氯胺-T氧化后进行放射性碘化，并通过色谱法分离标记物。125I-酚妥拉明在豚鼠脑中不能选择性地结合α-肾上腺素能受体，而125I-BE 2254衍生物能快速、可逆且高亲和力地结合这些受体，解离常数为230 pM。在低浓度的125I-BE 2254（小于100 pM）时，约90%的结合放射性配体是特异性结合的，在这些条件下的药物置换研究表明，该配体主要结合到肾上腺素能受体的α1亚类上。对肾脏和平滑肌膜制剂的结合测量表明，125I-BE 2254也可能是研究外周组织中α-肾上腺素能受体的有用工具。125I-BE 2254的高比活性允许在受体测定和配体置换测量中使用极少量的膜材料，例如每个测定管250微克，这相对于使用现有的放射性配体如3H-哌唑嗪具有显著优势，3H-哌唑嗪需要约40倍的组织量。
