IN-VITRO EFFECTS OF TRAPIDIL ON FATTY-ACID AND PROSTAGLANDIN METABOLISM IN PLATELETS

The effects of trapidil, a coronary vasodilator and platelet aggregati on inhibitor, on fatty acid metabolism and prostaglandin (PG) formatio n in platelets were studied using platelet suspensions from six normal subjects. The addition of trapidil to fatty acids in platelet phospho lipids decreased palmitoleic acid and arachidonic acid, and increased an unidentified substance, X2 (palmitoleic acid, P < 0.05; arachidonic acid, P < 0.05; X2, P < 0.05). Thrombin stimulation following the add ition of trapidil resulted in an increase in stearic acid and a decrea se in arachidonic acid, compared with the trapidil-free control sample s (stearic acid, P < 0.05; arachidonic acid, P < 0.02). The addition o f trapidil tended to increase immunoreactive PGE (iPGE) and iPGF dose- dependently. On the other hand, thrombin stimulation following the add ition of trapidil decreased the formation of thromboxane B2 (TXB2) sig nificantly compared with the levels of TXB2 in the trapidil-free sampl es (10 mug/mL trapidil, P < 0.005, 100 mug/mL trapidil, P < 0.001). Th ese results show that trapidil increased arachidonic acid mobilization in the platelets.