Trends in the development of antithrombotic agents

Investigations into the Benzofuran Series LVI. Anti-Thrombotic Activity of Inicarone

In addition to its fibrinolytic effects, which have been previously described, inicarone inhibits platelet adhesiveness and aggregation in animals. It therefore possesses the properties required of an anti-thrombotic agent. Actually, inicarone is able not only to increase the thrombus formation time, but also to lyse experimental thrombus created under severe conditions. It may be therefore reasonably assumed that inicarone could be effective in man in all syndromes involving thrombotic episodes.

Effects of S-8527 (1, 1-bis (4'-(1"-carboxy-1"-methylpropoxy) phenyl) cyclohexane), a new hypolipidemic compound, on platelet aggregation, adhesiveness and blood coagulation in rats

Effects of S-8527 (1,1-bis[4'-(1"-carboxy-1"-methylpropoxy) phenyl] cyclohexane) on platelet aggregation, adhesiveness and blood coagulation were examined in rats. In animals maintained on a semisynthetic diet containing sucrose (62%) as the only carbohydrate source, platelet adhesiveness increased as compared with that in rats fed a normal chow pellet. Under these experimental conditions, oral dose of S-8527 (30-300 mg/kg) for 14 days decreased platelet adhesiveness and ADP-induced platelet aggregation, but did not decrease collagen-induced platelet aggregation. S-8527 also showed a slight but significant increase of R value of thrombelastograph. In rats which were fed a normal chow pellet oral dose of S-8527 for 14 days did not significantly affect the several tests of platelet function and blood coagulation. These results suggest that S-8527 normalizes the platelet function in a hyper-adhesive state, but does not affect the platelet function in a normal state.

Stress and the induction of intravascular platelet aggregation in the heart

Intravascular aggregation of platelets similar to that found in dogs after norepinephrine infusion was demonstrated using the electron microscope in the hearts of 20 of 23 rats subjected to two forms of stress (immersion in hot water, 7 of 8 rats; repeated small electric shocks to the feet, 13 of 15 rats). Only one of 14 unstressed rats was found to have similar intravascular platelet aggregates. These findings suggest that catecholamines secreted endogenously during stress are sufficient to cause platelets to aggregate intravascularly and raise the possibility that clinical myocardial infarction occurring during severe or prolonged stress may be caused by catecholamine-induced platelet thrombi which occur at, or travel to, and occlude a coronary artery already narrowed by previous atherosclerosis.

Intravascular platelet aggregation in the heart induced by stress

Sixteen rats, stressed by immersion in ice-cold water for 25-45 min, were found to have platelet aggregates in myocardial small vessels on electron microscopic study. None of six similar nonstressed control rats had platelets in myocardial vessels. It is concluded that stress, probably via catecholamine secretion that enhances platelet stickiness, can induce intravascular platelet aggregation. It is possible that this mechanism plays a part in the relationship between stress and acute clinical myocardial infarction.