Figure 2.

Pharmacological profile of the GW9508 and GW1100 at the GPR40 receptor. (a) The effect of GW9508, linoleic acid, α-linolenic acid, palmitoleic acid and cis-5,8,11,14,17-eicosapentaenoic acid on intracellular Ca²⁺ levels was examined in HEK-293 cells expressing the human GPR40 receptor. pEC₅₀ values obtained were GW9508 (pEC₅₀=7.32±0.03; n=4), linoleic acid (pEC₅₀=5.65±0.06; n=4), α-linolenic acid (pEC₅₀=5.94±0.03; n=4), palmitoleic acid (pEC₅₀=5.86±0.05; n=4) and cis-5,8,11,14,17-eicosapentaenoic acid (pEC₅₀=5.73±0.04; n=4). (b) Inhibition of GW9508 and linoleic acid induced intracellular Ca²⁺ increase by GW1100, a selective GPR40 receptor antagonist. GW1100 produced a concentration-dependent decrease in intracellular Ca²⁺ response to an EC₈₀ concentration of GW9508 (pIC₅₀=5.99±0.03; n=4) and linoleic acid (pIC₅₀₌5.99±0.06; n=4). (c) The effect of increasing concentrations of GW1100 on GW9508-induced luciferase activity in a human GPR40-5 × Gal/Gal4-Elk1-luc⁺ CHO cell line reporter assay. Cells were preincubated with GW1100 for 15 min before addition of GW9508. GW1100 produced a concentration-dependent rightward shift in the GW9508 curve followed by a depression of the signal. This is consistent with a non-competitive mode of antagonism in the presence of a significant GPR40 receptor reserve. (d) The selectivity of GW1100 in the human GPR40-5 × Gal/Gal4-Elk1-luc⁺ CHO cell line reporter assay was confirmed using Thrombin as a control stimulus. Data represent the mean±s.e.m.