ABSTRACT
Although the concept of receptors is more than 2000 years old, 1, 2 the importance of receptors in physiology and pathophysiology has gained recognition only over the last several decades. In the last several years, the design of potential radiopharmaceuticals based upon receptor-ligand interactions has been enthusiastically embraced. 3-6 Such radiopharmaceuticals offer a unique opportunity to characterize pathological states noninvasively by measuring changes in receptor properties, e.g., concentration of receptor in the target tissue and/or the affinity of the receptor for the natural hormone or synthetic analog. Recent reviews of receptors and disease have been somewhat limited in scope, 7,8 partly because of the rapidly increasing number of systems where changes in receptor properties have been identified, although often not thoroughly characterized. We shall present a more extensive review of the available, documented changes in receptor properties in man as a function of a variety of physiological states. We also comment on model systems which may apply to man.
