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.


METHODS
Femoral arterial rings from rats were studied in organ baths. The vascular segments were constricted with phenylephrine after 20 min of preincubation with the triglyceride-rich fat emulsion Intralipid, free fatty acids (16:0, 18:1, 18:3) bound to bovine serum albumin, or very low density lipoproteins. Endothelium-dependent and endothelium-independent relaxations were determined after administration of acetylcholine and nitric oxide donors, respectively.


RESULTS
Preincubation with Intralipid caused a concentration-dependent impairment of endothelium-dependent but not endothelium-independent 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 of the antioxidant vitamin C partly reversed the impairment of the endothelium-dependent relaxation induced by Intralipid and free fatty acids.


CONCLUSIONS
The present study demonstrates that the triglyceride-rich fat emulsion Intralipid and individual FFAs impair endothelium-dependent relaxation of arterial rings from rat, whereas triglycerides in the form of VLDL do not affect endothelial function. The finding that the antioxidant vitamin C partly reverses this impairment indicates the involvement of oxidative mechanisms.
Lundman
P
P
Department of Cardiology, Karolinska Hospital, SE-171 76, Stockholm, Sweden. pia.lundman@medks.ki.se
Tornvall
P
P
Nilsson
L
L
Pernow
J
J
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001205:Ascorbic Acid / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005217:Fat Emulsions, Intravenous / Q000494:pharmacology*; D005230:Fatty Acids, Nonesterified / Q000494:pharmacology*; D005263:Femoral Artery; D066298:In Vitro Techniques; D008079:Lipoproteins, VLDL / Q000494:pharmacology*; D008297:Male; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D019335:Nitroarginine / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D019301:Oleic Acid / Q000494:pharmacology; D019308:Palmitic Acid / Q000494:pharmacology; D010396:Penicillamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014280:Triglycerides / Q000494:pharmacology*; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology; D019323:omega-N-Methylarginine / Q000494:pharmacology
D000975:Antioxidants; D004791:Enzyme Inhibitors; D005217:Fat Emulsions, Intravenous; D005230:Fatty Acids, Nonesterified; D008079:Lipoproteins, VLDL; D020030:Nitric Oxide Donors; C110881:S-nitro-N-acetylpenicillamine; D014280:Triglycerides; D014665:Vasodilator Agents; D009599:Nitroprusside; D019335:Nitroarginine; D019323:omega-N-Methylarginine; D019301:Oleic Acid; D019308:Palmitic Acid; D019001:Nitric Oxide Synthase; D010396:Penicillamine; D000109:Acetylcholine; D001205:Ascorbic Acid