Cholecystokinin (CCK) regulates various gastrointestinal functions through specific receptors. The mechanisms responsible for disorders of these functions could be elucidated by non-invasively localizing CCK receptors and quantifying their number in vivo. MK-329 is a highly selective and very high affinity antagonist at the peripheral CCK receptor. We investigated the in vivo binding of [3H](±)-MK-329 in mice to determine if binding to CCK receptors could be detected after systemic administration of the tracer. The uptake of [3H](±)-MK-329 increased in the pancreas from 5 min to 4 h after administration. The binding was saturable, stereospecific, and more than 80% specific. A total/non-specific binding ratio of 43 was reached at 8 h post-injection. The pancreas was the only organ where specific binding could be detected. Our results suggest that MK-329 labeled with a positron emitter such as C-11 could be used with positron emission tomography to image and quantify peripheral CCK receptors in man.
- (In vivo binding)
- CCK receptor antagonists
- CCK receptors (peripheral)
- PET (positron emission tomography)
ASJC Scopus subject areas