ABSTRACT
The mechanism of decreasing platelet aggregation by fish oil rich in n-3 fatty acids was studied in rabbits and rats. These animals were randomly divided into four groups. In rats, group Ⅰ was fed a basal diet; group Ⅱ was fed a high fat diet containing 7.5% lard, 0.25% bile salts, 0.5% cholesterol, group Ⅲ and Ⅳ received the diet with 5% lard, 0.25% bile salts,0.5% cholesterol and 0.5 ml fish oil or 0.5ml olive oil respectively. In rabbits, group Ⅰ was fed a basal diet; group Ⅱ received 20g diets containing 10.4% lard, 2.5% cholesterol, then, some basal diet; group Ⅲ and Ⅳ received 20g diets with 4.2% lard, 2.5% cholesterol and 2 ml fish oil or olive oil respectively, then, some basal diet. Fish oil contained 20% EPA and 50% DHAThree months later, plasma TXB2/6KPGF1? ratios were 1.4, 2.2, 1.0, 1.7. Plasma TXB2, cholesterol, serotonin, calcium, fibrinogen and blood viscosity were significantly lowered in group Ⅲ as compared with group Ⅱ. Platelet cAMP was greatly increased in group Ⅲ than that in group Ⅱ n-3 fatty acids in platelet, plasma and tissues such as liver and heart were definitively higher in group Ⅲ.These experiments showed that fish oil inhibited platelet aggregation and thrombosis formation as a consequence of changing the fatty acids composition in tissue membrane and decreasing TXA2/PGI2 ratio which may stimulate platelat cAMP synthesis and then decrease some agglutinating factors such as serotonin and calcium etc, released from platelet. On the other hand fish oil lowered blood cholesterol, which may change blood cell membrane fluidity, lowered blood fibrinogen and viscosity, so the situation of blood platelet and its surroundings could be improved.