Fig 2: Immunohistochemical studies with an anti-FFA4 antibody on porcine lower esophageal sphincter. Tissue sections were incubated with an anti-FFA4 (GTX100364) antibody and stained with DAB (3,3'-diaminobenzidine tetrahydrochloride) as a chromogen. Free fatty acid receptor 4 immunostaining was detected in the smooth muscle (SM) of the paraffin-embedded LES sling (A) and clasp (B) muscles (magnification 400×). The negative controls in the sling (C) and clasp (D) muscle were stained with equimolar concentrations of normal rabbit IgG (magnification 400×).

Fig 3: The effect of FFA1 and FFA4 agonists on porcine lower esophageal sphincter. The ability of specific free fatty acid receptor 1 (FFA1) agonists, FFA4 agonists or methanol (vehicle) to induce relaxation of the porcine lower esophageal sphincter (LES) sling (A) and clasp (B) muscle strips. The FFA1 specific agonists, GW9508, TUG424, and fasiglifam induced marked relaxation of the porcine LES muscle in a dose-dependent manner. The FFA4 specific agonists, TUG891 and GSK137647, produced mild relaxations of the porcine LES muscle. The values are expressed as a percent of an endothelin 1 (300 nM)-induced contraction. The results given are from at least four experiments. The vertical bars represent ± standard error of the mean (SEM). The * represents a significant difference compared with the relaxation induced by an equivalent concentration of methanol (p < 0.05). The # indicates a significant difference compared with the relaxation induced by an equivalent concentration of fasiglifam (p < 0.05).