Multiple sites of interaction between prostaglandins and non-steroidal anti-inflammatory agents

Several non-steroidal anti-inflammatory agents (NSAIA) are shown to inhibit the net production of prostaglandin (PG)- like activity from arachidonic acid by a cell-free preparation of guinea-pig lung. Moreover, these agents also antagonize PGE₁-induced contractions of the isolated gerbil colon. The anti-spasmogenic effects are reversible and specific. At high concentrations, indomethacin and mefenamic acid interfere with the binding of PGE₁ to a broken cell preparation of rat epididymal adipocytes. Taken together the data indicate that NSAIA interact with prostaglandins at multiple sites and are consistent with the suggestions reported previously that NSAIA may have multiple actions.