Principles of membrane receptor physiology and their application to clinical medicine.

The clinical involvement of membrane receptors for hormones, neurotransmitters, and other molecules of interest is reported with increasing frequency. In this review, the terminology of the hormone-receptor field is defined, and the current concepts of the participation of membrane receptors in the mechanism of hormone action are outlined. Several major developing concepts of receptor regulation and function, including spare receptors and down regulation of receptor number, provide a basis for understanding the physiology and pathophysiology of cellular sensitivity to specific hormones. The relation of these concepts to the pathophysiology of various metabolic disorders is discussed. Clinical disorders in which membrane receptors play a central role are reviewed, including Graves' disease and myasthenia gravis, which involve antireceptor antibodies, and familial hypercholesterolemia and various conditions of hormone resistance that often involve a marked decrease in receptor number as the primary pathogenic factor. The significance of receptor physiology in other selected areas of clinical medicine is discussed.