3. Discussion
In this study, we explored whether the beneficial effects of EPA and DHA supplementation on vascular function might be linked to HDL structure. Both HDLs and-3 fatty acids have been shown to improve endothelial function [Our results showed that 2 g/d of EPA and DHA effectively improved endothelial function assessed using FMD. This beneficial effect of n-3 on vascular function is still controversial [Once we demonstrated the beneficial effect of EPA and DHA on vascular function, the next step was to explore whether HDLs effectively carried both n-3 fatty acids. Our results showed a significant increase in EPA and DHA as components of lipids carried by HDLs. Such increments were similar to that observed in the plasma of patients with high cardiovascular risk treated with 1800 mg/d of n-3 as fish oil, and who reached 220.3% and 68.3% of EPA and DHA increase in plasma, respectively [Besides EPA and DHA, three n-6 fatty acids significantly decreased during n-3 supplementation, the precursor of arachidonic acid, and two of its metabolites as mentioned in the results section. This observation suggests that HDLs, EPA, and DHA compete with other long-chain fatty acids for key enzymes related to inflammatory processes. Of particular interest, is the increase in the EPA-to-AA ratio of about twice the basal value. EPA and AA may compete for the active site of cyclooxygenases (COX’s) since both fatty acids are substrates of these enzymes [Polyunsaturated fatty acids are more fluid than monounsaturated or saturated fatty acids; consequently, the increase in n-3 content in HDLs may compromise the stability of the particle via the modification of its surface tension, which is fundamental for the metabolism and function of these lipoproteins [Once we confirmed that HDLs were enriched with n-3 fatty acids, we further explored the possibility that EPA and DHA contribute to endothelial function improvement via these lipoproteins. For this, we pre-incubated rat aorta rings with HDLs from patients and then contracted them with epinephrine. The addition of increasing doses of acetylcholine induces the endothelium-dependent relaxation of vascular smooth muscle [Finally, long-term effects of EPA and DHA that have been observed in some tissues [