Use of a semi-automated, robotic radioimmunoassay to measure cAMP generated by activation of DP-, EP2-, and IP-prostaglandin receptors in human ocular and other cell types.

The aim of these studies was to compare the effects of several prostaglandin agonists on adenylyl cyclase activity in embryonic bovine tracheal (EBTr) cells, transformed human nonpigmented ciliary epithelial (NPE) cells and National Cancer Bank (NCB-20) cells. These cell types have been shown to express DP, EP2 and IP prostaglandin (PG) receptors, respectively. Cyclic AMP (cAMP) generation was measured by manual and semi-automated radioimmunoassay (RIA) techniques. ZK118182 (EC50 = 10-27 nM), PGE2 (EC50 = 21-27 nM) and PGI2 (EC50 = 3.5-4 nM) had the highest potency at the DP, EP2 and IP receptors, respectively. A plot of potency (EC50) values generated with both techniques showed a high degree of correlation for all three receptors. These studies provide further characterization of prostanoid receptor functional responses in three cell types and demonstrate the advantages of a semi-automated RIA method for the analysis of the second messenger cAMP.