A triglyceride-rich fat emulsion and free fatty acids but not very low density lipoproteins impair endothelium-dependent vasorelaxation

Objective: To investigate the effects of triglycerides and free fatty acids on endothelium-dependent and endothelium-independent vasorelaxation. Metho ds: Femoral arterial rings from rats were studied in organ baths. The vascu lar segments were constricted with phenylephrine after 20 min of preincubat ion with the triglyceride-rich fat emulsion Intralipid (R), free fatty acid s (16:0, 18:1, 18:3) bound to bovine serum albumin, or very low density lip oproteins. Endothelium-dependent and endothelium-independent relaxations we re determined after administration of acetylcholine and nitric oxide donors , respectively. Results: Preincubation with Intralipid (R) caused a concent ration-dependent impairment of endothelium-dependent but not endothelium-in dependent relaxation, Very low density lipoproteins did not affect vascular function. All free fatty acids impaired endothelium-dependent relaxation, whereas endothelium-independent relaxation was unaffected. Administration o f the antioxidant vitamin C partly reversed the impairment of the endotheli um-dependent relaxation induced by Intralipid (R) and free fatty acids. Con clusions: The present study demonstrates that the triglyceride-rich fat emu lsion Intralipid (R) and individual FFAs impair endothelium-dependent relax ation of arterial rings from rat, whereas triglycerides in the form of VLDL do not affect endothelial function. The finding that the antioxidant vitam in C partly reverses this impairment indicates the involvement of oxidative mechanisms. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.