Williams D W, Summers R J
Department of Pharmacology, University of Melbourne, Parkvile, Vic. Australia.
Comput Methods Programs Biomed. 1990 Jun;32(2):137-9. doi: 10.1016/0169-2607(90)90093-o.
Many tissues possess two classes of binding sites for a drug. To estimate the proportions of each it is necessary either to use selective ligands or to perform competition experiments in which the binding of a radioligand is inhibited by a selective unlabeled ligand. However, this method will only be accurate provided the radioligand is non-selective. A selectivity of 2- to 3-fold for one receptor may produce errors of 50% or more in the estimates, depending on the concentration of radioligand chosen. Since most ligands are selective to some extent simple estimates will often provide inaccurate information. The computer program described here (SIMUL) determines the proportions of receptor subtypes by considering the relative affinities of the competing agent for the receptor subtypes, the selectivity of the radioligand and their associated concentrations.
许多组织对一种药物具有两类结合位点。为了估计每类结合位点的比例，要么使用选择性配体，要么进行竞争实验，即放射性配体的结合被选择性未标记配体抑制。然而，只有在放射性配体是非选择性的情况下，这种方法才会准确。对一种受体2至3倍的选择性可能会在估计中产生50%或更高的误差，这取决于所选择的放射性配体的浓度。由于大多数配体在某种程度上具有选择性，简单的估计往往会提供不准确的信息。这里描述的计算机程序（SIMUL）通过考虑竞争剂对受体亚型的相对亲和力、放射性配体的选择性及其相关浓度来确定受体亚型的比例。
