USE OF A SEMI AUTOMATED, ROBOTIC RADIOIMMUNOASSAY TO MEASURE CAMP GENERATED BY ACTIVATION OF DP-PROSTAGLANDIN, EP2-PROSTAGLANDIN, AND IP-PROSTAGLANDIN RECEPTORS IN HUMAN OCULAR AND OTHER CELL-TYPES

The aim of these studies was to compare the effects of several prostag landin agonists on adenylyl cyclase activity in embryonic bovine trach eal (EBTr) cells, transformed human nonpigmented ciliary epithelial (N PE) cells and National Cancer Bank (NCB-20) cells. These cell types ha ve been shown to express DP, EP, and IP prostaglandin (PG) receptors, respectively. Cyclic AMP (cAMP) generation was measured by manual and semiautomated radioimmunoassay (RIA) techniques. ZK118182 (EC50 = 10-2 7 nM), PGE(2) (EC50 = 21-27 nM) and PGI(2) (EC50 = 3.5-4 nM) had the h ighest potency at the DP, EP2 and IP receptors, respectively. A plot o f potency (EC50) values generated with both techniques showed a high d egree of correlation for all three receptors. These studies provide fu rther characterization of prostanoid receptor functional responses in three cell types and demonstrate the advantages of a semi-automated RI A method for the analysis of the second messenger cAMP.