Evaluation of ( - )[18F]fluoroethoxybenzovesamicol as a new PET tracer of cholinergic neurons of the heart

Abstract

18F-labeled ( - )fluoroethoxybenzovesamicol [( - )FEOBV] is a novel PET tracer which binds to the vesicular acetylcholine transporter of cholinergic neurons. To evaluate the in vivo binding specificity and kinetic properties of ( - )FEOBV, studies were performed in isolated working rat hearts. External [gamma],[gamma]-coincidence monitoring of hearts indicated high extraction of radiotracer by the myocardium and rapid wash-out of unbound tracer (>90% of maximal accumulation) within 5 min. Inclusion of ( - )vesamicol (10 [mu]M) throughout perfusion decreased the retention of ( - )FEOBV by 71% (P P in vivo studies with PET is likely to be limited by the low rate of specific binding in myocardium consistent with the low density of cholinergic neurons in the heart.