Figure 7. Effect of two B₂-receptor antagonists and a cyclooxygenase (COX) inhibitor on release of total PGs from h-CM cells and CHO-B₂ cells. A: Concentration-response studies with BK were conducted in primary h-CM cells in the absence and presence of the fixed concentration of receptor antagonists and enzyme inhibitor (all at 1 µM final) preincubated with the cells for 5 min before BK was added. Note that, although bromfenac completely abolished PG synthesis and release, WIN-64338 and HOE-140 caused a right-ward shift of the BK-induced PG release, indicative of competitive inhibition at the B₂ receptor, with HOE-140 more potent than WIN-64338. B: The results obtained using CHO-B₂ cells and the same experimental protocol as described above for the h-CM cells. Both sets of data are mean±SEMs from three experiments for each cell type.