Synergistic interaction and platelet inhibitory agonists.

Marked synergistic interaction is observed between two platelet excitatory agonists neither of which cause inhibition of adenylate cyclase. No synergistic interaction is observed between the platelet inhibitory agonists PGI2, PGD2 and adenosine nor between ADP and adrenaline when acting as inhibitory agonists for adenylate cyclase. The studies suggest that synergistic interaction between platelet agonists may be restricted to the excitatory responses.