为进一步探讨衰老过程中脑中Ｍ型胆碱能受体的随龄性变化，采用放射配基结合实验，检测了３，１２，２０，２５月龄Ｗｉｓｔａｒ大鼠脑组织中Ｍ胆碱能受体的最大结合容量（Ｂｍａｘ）和解离常数（Ｋｄ），结果如下：（１）４组大鼠脑组织中Ｍ受体的最大结合容量随年龄增长依次减少，各组间均有显著差异；（２）４组大鼠脑组织中Ｍ受体的解离常数随年龄依次减小，表明受体的亲和力逐渐升高。 In order to further investigate the age-dependent changes of M cholinergic receptors in the brain during aging, radioligand binding assay was used to detect M cholinergic receptors in Wistar rats at 3, 12, 20 and 25 months (Bmax) and dissociation constant (Kd). The results are as follows: (1) The maximal binding capacity of M receptor in brain tissue of 4 rats decreased with age, with significant difference among all groups; ( 2) The dissociation constants of M receptor in the brain tissue of four groups decreased with age, indicating that the affinity of the receptor gradually increased.