Adrenomedullin exerts its action on RA fibroblast adhesion through CLR/RAMP receptors. RA-FLSs were incubated for 30 minutes with various concentrations of (22-52)AM, or H-89, or for 24 hours with siRNA-RAMP-2 and then with or without soluble adrenomedullin (AM) for 1 hour. (22-52)AM, H-89, and siRNA RAMP-2 inhibited the adhesion-enhancing effect of AM. Bars indicate mean ± SEM. ***P < 0.0001; ###P < 0.0001 versus 10-7 M AM, and §P < 0.05. Results are given as the ratio of OD in each condition over control OD without AM and reported as mean ± SEM of two experiments (different donors) performed in quadruplicate. (a) Dose-dependent effect of (22-52)AM on basal and AM-stimulated RA-FLSs adhesion. (b) Dose-dependent effect of H-89 on basal and AM-stimulated RA-FLSs adhesion in each condition over OD of control. (c) Dose-dependent effect of siRNA RAMP-2 on AM-stimulated RA-FLSs adhesion in each condition over OD of control.