FIGURE 2.
Binding and biological activity of GI181771X at wild-type CCK receptors. Shown in the inset is the chemical structure of the 1,5-benzodiazepine ligand, GI181771X, with the positions around the benzodiazepine ring numbered. Also shown are curves representing the abilities of this compound to compete for the saturable binding of the CCK-like radioligand ,125I-d-Tyr-Gly-[(Nle28,31)CCK-26–33], to CHO-CCK1R and CHO-CCK2R cells (left panel), and its abilities to stimulate these cells to increase intracellular calcium responses (right panel). Saturable binding of the CCK-like radioligand was determined by competition with 1 μm CCK, and biological responses were determined relative to the maximal response of the cells to CCK. Data represent mean ± S.E. of values from five to eight independent experiments performed in duplicate.