DIFFERENTIAL-EFFECTS OF DIETARY FATS ON AGGREGATION OF PLATELETS FROM RATS

Diets containing either n-3 fatty acids (menhaden oil) or n-6 fatty acids (corn oil) as the lipid source were fed to rats for 1 week to alter the fatty acid composition of platelet membrane phospholipids. Platelets from both dietary groups of rats were isolated by gel-filtration and challanged with agonists that induce platelet responses by different mechanisms: collagen; the thromboxane mimetic, U46619; and fluoride. The ingestion of menhaden oil resulted in a lower responsiveness of platelets with the first two agonists, which act through membrane receptors. However, aggregation induced by fluoride, which bypasses outer membrane receptors, did not differ between platelets from the two dietary groups. These results suggest that dietary marine oils act to dampen cellular sensitivity to signals initiated by pro-aggregatory agonists binding to membrane receptors rather than to signals produced indiscriminately at the post-receptor level.