Selection, design and evaluation of new radioligands for PET studies of cardiac adrenoceptors

Changes in the numbers of human cardiac adrenoceptors (ARs) are associated with various diseases, such as myocardial ischemia, congestive heart failure, cardiomyopathy and hypertension. There is a clear need for capability to assess human cardiac ARs directly in vivo. Positron emission tomography (PET) is an imaging technique that provides this possibility, if effective radioligands can be developed for the targeted ARs. Here, the status of myocardial AR radioligand development for PET is described. Currently, there exist effective radioligands for imaging β-ARs in human myocardium. One of these, [${}^{11}\text{C}$](S)-CGP 12177, is applied extensively to clinical research with PET, sometimes with other tracers of other aspects of the noradrenalin system. Alternative radioligands are in development for β-ARs, including β₁-selective radioligands. A promising radioligand for imaging myocardial α₁-ARs, [${}^{11}\text{C}$]GB67, is now being evaluated in human PET experiments.