Analysis of platelets in nonhuman primates:: II. Effects of varying dietary fatty acid ratios on platelet ultrastructure and function

Abstract

The effects of varying dietary fatty acid composition on in vitro aggregation and ultrastructure of African green monkey platelets are reported. Platelets from animals maintained on either a control diet (30% calories from fat; polyunsaturated:saturated:monounsaturated = 1:2.3:2.7) or a diet approximating that suggested by the Senate Select Commuttee on Nutrition and Human Needs (P:S:M = 1:1:1) aggregated maximally with 20 μ M ADP to a level of 65%. With lesser amounts of ADP, the maximum aggregation decreased proportionally to a low of 25% when using 3 μ M ADP. This aggregation pattern was signficantly altered when the animals were switched to a safflower oil-enriched diet which provided more polyunsaturated fatty acid (PUFA) (P:S:M = 2:1:1). With the high PUFA diet, platelet aggregation using ADP increased to a range of 45–85% depending upon the concentration of aggregating agent used. Thrombin-induced aggregation was unaltered by dietary change. The ADP hypersensitivity in platelets with the PUFA diet paralleled a significant drop in plasma HDL. Concomitantly, large lipid-like droplets were consistently observed in the cytoplasm of platelets obtained during the high-PUFA diet period. Platelet aggregation and ultrastructure and plasma HDL levels returned to normal with resumption of the control diet. The platelet hypersensitivity to ADP aggregation and the cytoplasmic lipid were again observed when the animals were returned to a PUFA diet containing 40% calories from fat. Results substantiate the suggestion that under certain conditions dietary PUFAs alter circulating platelets. The biochemical mechanism for the alterations remains to be elucidated.