Figure 1. Response of ACTOne OPRL1 cell line & parental cell line to Orphanin FQ.ACTOne OPRL1 cells and parental cells (Cat# 341467) were plated overnight in 20 ml culture medium on a BD Biocoat 384 well plate. The next day, cells were dye-loaded with 20 ml/well of 1X Dye-loading solution (ACTOne Membrane Potential Assay Kit). After 2 hours of incubation at room temperature, two readings were obtained prior to and 30 min after the addition of Orphanin FQ. Ratios of the two readings (F/F0) are plotted in the figure. A. Dose response curve of Orphanin FQ in ACTOne OPRL1 cell line. EC50 = 0.75 nM in the presence of PDE inhibitor Ro20-1724 and b-adrenoceptor agonist isoproterenol. B. Parental cells do not respond to Orphanin FQ.