Kaiser G, Wiemer G, Dietz J, Palm D
Blut. 1978 Dec 15;37(6):295-306. doi: 10.1007/BF01007864.
By means of the radioactive antagonist ligand (3H)(-) dihydroalprenolol (DHAP) specific binding sites were identified in membrane preparations from red blood cells from rats. These specific sites were characterized as beta-adrenoceptors because of the following reasons: Specific binding of DHAP (in contrast to unspecific binding) was dependent on temperature and time of incubation. Furthermore, specific binding of DHAP showed saturability, temperature-dependent reversibility and high affinity (KD-value of DHAP = 6.51 nM). Specific binding of DHAP was competitively inhibited by beta-adrenergic antagonists (pindolol greater than alprenolol greater than or equal to propranolol greater than practolol) and agonists (isoprenaline greater than adrenaline). The (-) enantiomers of pindolol and isoprenaline showed pronounced higher affinities for the receptor sites than the respective (+) enantiomers. The receptor density in the membrane preparations (pmoles/mg protein) was strongly dependent on the degree of reticulocytosis: The Bmax-values increased more than 4 to 5 fold without alteration of the respective KD-values when reticulocyte counts were enhanced from 3 to 80% treatment of the animals with increasing doses of acetyl phenylhydrazine.
通过放射性拮抗剂配体（3H）（-）二氢心得安（DHAP），在大鼠红细胞的膜制剂中鉴定出特异性结合位点。这些特异性位点被表征为β-肾上腺素能受体，原因如下：DHAP的特异性结合（与非特异性结合相反）取决于孵育温度和时间。此外，DHAP的特异性结合表现出饱和性、温度依赖性可逆性和高亲和力（DHAP的KD值=6.51 nM）。DHAP的特异性结合受到β-肾上腺素能拮抗剂（吲哚洛尔＞心得安≥普萘洛尔＞普拉洛尔）和激动剂（异丙肾上腺素＞肾上腺素）的竞争性抑制。吲哚洛尔和异丙肾上腺素的（-）对映体对受体位点的亲和力明显高于各自的（+）对映体。膜制剂中的受体密度（pmoles/mg蛋白质）强烈依赖于网织红细胞增多程度：当用递增剂量的乙酰苯肼处理动物，使网织红细胞计数从3%提高到80%时，Bmax值增加了4至5倍以上，而各自的KD值没有改变。
