Fig. 3.

Biological activity characteristics of GI224329. Shown are biological response curves reflecting the ability of 0.1 μM GI224329 (●) to shift CCK-stimulated intracellular calcium responses (○) to the right (A) and the ability of various concentrations of GI224329 (●) to inhibit intracellular calcium responses stimulated by 0.1 nM CCK in CHO-CCK₁R cells (B). GI224329 acted as a competitive antagonist that inhibited the calcium response elicited by CCK. K_b (40 ± 10 nM) and IC₅₀ (50 ± 20 nM) values were in a similar range. Data are expressed as means ± SEM of values from three independent experiments performed in duplicate.