Effects of acetylsalicylic acid and dietary intervention on primary hemostasis.

There is evidence that pathological aggregation of platelets in atherosclerotic arteries is initiated by hemorrhage through fissures in atheromatous plaques. Bleeding time determination reflects in vivo the physiologic function of platelets in their aggregation in injured vessels and can be used as a relevant model for primary hemostasis in investigations with antithrombotic aims. Acetylsalicylic acid is known to cause prolongation of bleeding time by inhibiting prostaglandin biosynthesis. Recent experiments have shown that dietary supplementation with omega-3 polyunsaturated fatty acids results in prolongation of bleeding time and decreased platelet aggregability. This paper is mainly concerned with the effect of different doses of aspirin (3.5 mg/kg, 5 mg/kg, and 10 mg/kg), and fish diets rich in omega-3 polyunsaturated fatty acids, on bleeding time and platelet aggregation. The effects of aspirin separately, as well as aspirin administration during dietary intervention, will be described. Administration of all three dose levels of aspirin prolonged bleeding time significantly (p less than 0.001). The effect of aspirin on bleeding time was dose-dependent and an optimum interval was found. A fish diet, rich in omega-3 polyunsaturated fatty acids, causes bleeding time prolongation and decreased platelet aggregability similar to those caused by aspirin. Aspirin taken during this diet prolonged bleeding time by more than the sum of the increases in bleeding time caused by aspirin and the diet with omega-3 polyunsaturated fatty acids, separately, but the synergism was not significantly more than additive. These observations suggest that fish diets affect primary hemostasis by mechanisms different from those of aspirin. Dietary intervention may therefore enhance the antithrombotic effects of aspirin.