Pharmacological comparison of the alternatively spliced short and long CCK 2 receptors

The alternatively spliced, short and long cholecystokinin receptors (CCK 2S and CCK 2L ) were expressed in NIH3T3 cells, and compared using radioligand‐binding assays with identical buffer and incubation conditions. As judged by a saturation analysis, the selective CCK 2 ‐receptor antagonist radioligand [ 3 H]‐JB93182 did not discriminate between the CCK 2S or CCK 2L receptors. A global analysis of competition studies, using a range of structurally diverse, CCK‐receptor selective ligands, provided further evidence that these receptor subtypes were pharmacologically indistinguishable. However, when analysed individually a number of small, yet significant differences were observed with some of the compounds. These data are consistent with previous study that suggested a possible pharmacological difference between these isoforms, at least in terms of the CCK 2 ‐receptor antagonist, L‐365,260. However, it would appear that the pharmacological profile of these compounds is not consistent with their affinity at the putative G 1 /G 2 receptors previously described by Harper et al.British Journal of Pharmacology (2003) 140 , 218–224. doi: 10.1038/sj.bjp.0705423