The goal of these studies was to compare the effects of several prostaglandin (PG) receptor agonists on adenylyl cyclase activity in transformed human nonpigmented ciliary epithelial (NPE) cells. In order to define the pharmacology of the PG receptors present on these cells, cyclic AMP production was measured by both manual and robotic radioimmunoassay (RIA) techniques. In NPE cells, the rank order of potency for the PGs tested in the current study (n = up to 46) was PGE2 (EC50 = 67 nM) > 13,14-dihydro-PGE1 (EC50 = 231 nM) > 11-deoxy-PGE1 (EC50 = 500 nM) = 16,16-dimethyl-PGE2 (EC50 = 872 nM) = 11-deoxy-16,16-dimethyl-PGE2 (EC50 = 1135 nM) >> PGF2 alpha (EC50 > 10,000 nM) = PGD2 (EC50 > 10,000 nM) = PGI2 (EC50 > 10,000 nM). The EP2-receptor selective PG, butaprost, exhibited a potency of 212 nM (Emax = 55%). The response to 1 microM PGE2 was antagonized by AH6809 (IC50 = approximately 50 microM, Kb = 4 microM). The relative potencies of the EP agonists mentioned above were significantly weaker in EbTr and NCB-20 cells expressing DP and IP receptors, respectively (1). These data provide a detailed pharmacological identification and characterization of EP2 receptors on NPE cells.