Dietary lipids, platelet function and arterial thrombosis in animals and man.

It is now generally accepted that the type and amount of dietary fat can affect the genesis and course of experimental atherosclerosis (Vles et al. Moreover, epidemiological studies clearly indicate that the type of dietary fat has a distinct influence on coronary artery disease (CAD) which is one of the clinical Human prospective studies also show that diets low in long-chain saturated fatty acids and enriched with linoleic acid are beneficial to CAD Since blood platelets are instrumental in arterial thrombosis, and arterial thrombosis is implicated in atherosclerosis and its complications (Chandler, 1982), the dietary fat effect on atherogenesis may, at least in part, be mediated by the influence on platelet function and arterial thrombosis. Effect of type of dietary fat on arterial thrombosis in a rat model Arterial thrombosis tendency was measured in rats, using a newly-developed model (Hornstra & Vendelmans-Starrenburg, 1973) which is based on the introduction of a loop-shaped polyethylene cannula into the abdominal aorta of male animals. Endothelial damage and flow disturbances cause the formation and growth of a platelet-rich, fibrin-poor mural thrombus, the structure of which is similar, in comparative phases of development, to that of natural arterial thrombi in man. The thrombus reaches an occlusive state after about 5 d. The moment of obstruction is indicated by a change in colour of the blood from light-red to dark blue. This can easily be observed, since the loop is made of translucent material and partly protrudes from the body. The period between insertion and complete obstruction of the loop is called the obstruction time (OT) and is a measure of the arterial thrombosis tendency of the animal : the longer the OT, the lower the thrombosis tendency. The usefulness of the aorta-loop technique was demonstrated by the observation that compounds influencing platelet aggregation and blood coagulation affect the arterial thrombosis tendency in a predictable manner. Moreover, known risk factors for atherosclerosis and thrombosis were shown to be associated with decreased obstruction times (Hornstra, 1980). T o study the effects of dietary fat on this model, 3-5-week-old male rats were given adequate diets, the carbohydrate moiety of which was isoenergetically replaced by various amounts of different oils and fats. Aorta-loops were inserted after 8-12 weeks. In a first series of experiments (Hornstra, 1971), it appeared that