Effects of dietary fish oil supplementation on platelet aggregability and platelet membrane fluidity in normolipemic subjects with and without high plasma Lp(a) concentrations.

The purpose of this study was to compare the relative effect of n-3 fatty acids on plasma lipids and platelet function in normolipemic subjects (n = 8) with plasma Lp(a) levels greater than 30 mg/dl and normolipemic subjects (n = 7) without detectable plasma Lp(a) concentrations. Six weeks of dietary supplementation (3.8 g EPA and 2.9 g DHA/d) significantly reduced (P less than 0.005) plasma TGs in both groups whereas no changes of plasma TC, LDL-C, HDL-C, and Lp(a), respectively, were found. Collagen- or thrombin-stimulated platelet aggregation and collagen- or thrombin-induced TXB2 generation from platelets decreased by approx. 45% in Lp(a)-negative and Lp(a)-positive platelet donors after a 6 week dietary intake. Four more weeks without n-3 supplementation restored the pretreatment values of TGs, platelet aggregability and TXB2 release. The biophysical properties of platelets from normolipemics with and without high plasma Lp(a) concentrations revealed a similar structural order of platelets at 37 degrees C using DPH, TMA-DPH, or 6-AS as fluorescent probes. Also similar temperature-dependent changes in platelet fluidity from 37 degrees C to 17 degrees C were observed in platelet preparations from Lp(a)-positive and Lp(a)-negative subjects. However, no subtle changes in the structural order of platelets due to nutrient intakes were found in all subjects (n = 15, 19-28 yrs) using fluorescence polarization technique. The present data suggest a similar in vitro platelet behaviour from normolipemic subjects with and without high plasma levels of Lp(a) (which is considered a risk for premature atherosclerosis) in contrast to platelet aggregability and platelet fluidity in certain hyperlipidemic stages.