Brodde O E
Biochem Pharmacol. 1982 May 1;31(9):1743-7. doi: 10.1016/0006-2952(82)90678-5.
The highly specific beta-adrenergic radio-ligand (+/-)-125 iodocyanopindolol (ICYP) was used to characterize the beta-adrenergic receptor subtype present in rat kidney. Binding of ICYP to membranes from rat kidney was of high affinity (KD = 68.9 pM) and saturable with 1.06 pmoles ICYP bound/g tissue wet wt at maximal occupancy of the sites. Analysis of inhibition of ICYP binding by beta 1- and beta 2-selective adrenergic drugs via pseudo-Scatchard ("Hoifstee') plots resulted in linear plots indicating the existence of a homogeneous population of beta-adrenergic receptors. From the resulting KD-values for practolol (2.2 microM), metoprolol (0.21 microM), zinterol (0.4 microM) and IPS 339 (0.046 microM) it is concluded that the beta-adrenergic receptor in rat kidney is of the beta 1-subtype. This subclassification is further supported by the fact that (-)-noradrenaline and (-)-adrenaline were equipotent in inhibiting ICYP binding. The beta-adrenergic agonists (-)-isoprenaline and zinterol bind to two distinct states of this beta 1-receptor, a high and low affinity state. GTP (10(-4) M) converts this heterogeneous binding into a homogeneous low affinity binding.
高特异性的β-肾上腺素能放射性配体（±）-125碘氰吲哚洛尔（ICYP）被用于鉴定大鼠肾脏中存在的β-肾上腺素能受体亚型。ICYP与大鼠肾脏膜的结合具有高亲和力（KD = 68.9 pM），并且在最大位点占有率时，每克组织湿重结合1.06皮摩尔ICYP时可饱和。通过伪Scatchard（“霍夫斯泰”）图分析β1和β2选择性肾上腺素能药物对ICYP结合的抑制作用，结果得到线性图，表明存在均一的β-肾上腺素能受体群体。从心得宁（2.2微摩尔）、美托洛尔（0.21微摩尔）、辛特罗尔（0.4微摩尔）和IPS 339（0.046微摩尔）的KD值可以得出结论，大鼠肾脏中的β-肾上腺素能受体是β1亚型。（-）-去甲肾上腺素和（-）-肾上腺素在抑制ICYP结合方面具有同等效力这一事实进一步支持了这种亚分类。β-肾上腺素能激动剂（-）-异丙肾上腺素和辛特罗尔与这种β1受体的两种不同状态结合，即高亲和力状态和低亲和力状态。GTP（10^-4 M）将这种异质性结合转变为均一的低亲和力结合。
