Effect of arachidonic acid on some inhibitors of the human platelet release reaction

Abstract

The inhibitory action of many agents on platelet aggregation and 5-hydroxy-tryptamine release inducible by epinephrine, comprising several non-steroidal anti-inflammatory drugs (NSAA)—indomethacin, acetylsalicylic acid, sodium salicylate, phenylbutazone and sulfinpyrazone—and other non-anti-inflammatory agents (NAA)—prostaglandin E 1, adenosine, dipyridamole, methysergide and cyproheptadine—can be prevented, and under special circumstanees reversed, by the prior addition to human platelet rich plasma of the essential fatty acid, 5,8,11,14 eicosatetraenoic (arachidonic) acid. Although this agent, and only its all cis stereosiomeric form, can per se induce aggregation and release, its protective action against the platelet-toxic drugs is attributed to its role as the key substance essential for prostaglandin enzymatic biosynthesis. the mechanism of NSAA action is evidently different from that of the non-anti-inflammatory agents.