ABSTRACT
The adrenergic system plays the major role in the regulation of heart rate and contractility and is abnormal in most of the major cardiac diseases. Beta-adrenergic receptors (ß-AR) are an important imaging target because they modulate the contractile response. Positron-emission tomography (PET) imaging of ß-ARs is a noninvasive procedure that helps to understand this receptor in cardiac disease. To understand the strengths and limitations of imaging studies of ß-AR in vivo, one must first understand how the receptor functions. The structural requirements for molecules to bind to ß-AR are well known. The binding of agonists, epinephrine and norepinephrine, to ß-AR creates a conformational change in the transmembrane receptor protein to release a subprotein inside the cell. Despite more than 15 years of a quantitative PET methodology for measuring ß-AR, there are few reports of imaging human ß-AR density in disease.
